First some background on Taekwondo. There are several organizations that certify ranking in Taekwondo. They all kind of look like each other, because they share the same exact roots. They branched off for different reasons, sometimes political, sometimes having to do with the emphasis of various techniques over other techniques, and other reasons. But they all teach the same basic techniques. Only rarely do you find a Taekwondo organization doing something truly different in a fundamental way than other organizations.
The two big, main TKD organizations are ITF (International TKD Federation) and WTF (World TKD Federation). These are just different organizations for the same art. They do have different forms (the choreographed routines), and their sparring rules are similar but differ in various ways.
You should read up on the differences between ITF and WTF first just to see what some of the differences are in those two main branches of TKD.
As for Jun Chong Taekwondo in particular, I can't really comment on it since I've not looked into the instructor's history. But I had a chance to look at their web site, and they look very credible. He's a 9th dan in Taekwondo and Hapkido. You should know that 9th dan is about as high as you can get, officially. Occasionally the 10th dan is officially awarded to people of distinction, usually those who have branched off and formed their own separate style.
Now, Jun Chong does not list his affiliation (ITF, WTF, or other) on his web site, I do not see. And he does not indicate which certifying organization his 9th dan is under. So those are two questions you'll need to ask if you're joining any Taekwondo school. Ask: What is your school's affiliation? What organization granted your head instructor his/her current rank?
When you know that, you'll be in a better position to determine if the school and instructor is legitimate. Because, there are many Taekwondo schools that have 9th and 10th degree black belt "grandmasters". They often aren't affiliated with any Taekwondo organization and have simply awarded themselves that rank by virtue of the fact that they are now head of their own organization. So that is a big problem with Taekwondo, and it's why your friend warned you about "McDojos".
Moving right along...
You mentioned that "realistic self-defense" was a concern for you. And you suggested that you're open to considering alternatives to Taekwondo such as boxing. I commend you on knowing what you want out of it and being open-minded about it. I say this, because, when I was starting out in martial arts, I just assumed that every martial art was realistic and just taught it differently. I have studied about a dozen martial arts before realizing what's what. And now I'll share that with you.
Before I do, however, just be aware that the following is my opinion based on my experience. I'm sure many others here will take issue with it. Others have their own opinions, and you should get as many opinions as you can and think about what you've heard. Whatever sounds the most reasonable to you should be what you go with.
First question: What does realistic self-defense look like to you?
To me, realistic self-defense means you know how to handle yourself confidently in 3 ranges of unarmed combat as well as having some knowledge of knife, stick, and maybe firearms. And your training involves partners actively trying to resist everything you're doing (as opposed to just letting you do things).
The 3 ranges of unarmed combat are: free-fighting, the clinch, and the ground.
In the free-fighting range, you and your opponent(s) are standing and not holding onto each other. You're just free to move around. This is where you punch, kick, knee, elbow, and head butt. There's also blocking and defensive strategy. It involves combos, decoying, and a lot of fancy footwork.
In the clinch range, you're still standing, but you and/or your opponent have gotten a hold of some sort. It restricts your ability to freely move. You can still punch, kick, and do many of the free-fighting range's techniques. But you just can't move completely freely.
And in the ground range, you and/or your opponent are on the ground (usually by way of a trip, a take-down, or a throw, in that order of likelihood). You'll learn how to choke and how not to be choked. You'll learn other submissions, elbow breaks, knee breaks. But it's mostly a game of position, some being more desirable than others. So you'll first practice getting in and out of positions.
And you'll learn how to avoid getting put into each of those ranges of fighting. So you'll know how to sprawl against someone shooting in to tackle you. You'll know how to get back to a standing position when on the ground. Etc. If you don't know all 3 ranges of fighting, you won't be very good at preventing someone from taking you somewhere you don't really know.
Realistic self-defense means you don't fear any of those 3 ranges of combat. You're okay if someone starts boxing with you, then grabs you. You're okay if someone dive-tackles you to try to take you to the ground. Etc.
You've trained for all of those possibilities. You're familiar with it. It doesn't take you completely by surprise or out of your element. You have a strategy that has been programmed into you so that it's mostly just auto-pilot for you. That is when you can say you are training realistically.
There's something else to consider, and that's resistance. In many martial arts, your partners mostly let you do stuff to them. They stand there and go with what you're doing. They sometimes even throw themselves into your throw, for example. They're usually told to act like what you're doing causes them to stop dead in their tracks, and then you perform a series of intricate motions in rapid sequence without ever once having to worry about your partner resisting you at all.
That is what you get in just about every martial art out there that doesn't do some kind of "live" sparring of some sort. That includes classical jujitsu, Aikido, the "self-defense" portion of most forms of karate (one-step sparring and "self-defense", although they do have punch/kick sparring), most forms of kung-fu, Hapkido, and so on.
Styles whereby you get with a partner who is then told to resist you as much as they can will prepare you for reality. Styles that have you partner with someone who will just act like what you're doing is working are not preparing you for reality.
Training with resisting partners is the primary way you get better at and more confident at fighting. If you can win against training partners who are actively trying to stop you from doing stuff while simultaneously trying to win against you, that predicts how you will do in a real fight.
Styles that train with resistance are: Brazilian Jiujitsu, MMA, Judo, wrestling, boxing, Muay Thai, kick-boxing, Sambo, and Shuai-Jiao. There are others. This isn't an exhaustive list.
Styles that do not train with resistance are: Taekwondo, most forms of Karate, most forms of Kung-Fu, Hapkido, Aikido, classical Jujitsu, Bujinkan Ninjutsu, Krav Maga, and many others.
If you want to see it through my eyes, go onto youtube right now and look at some of those arts. For example, Bujinkan Ninjutsu or Ed Parker Kenpo Karate. Sometimes you'll see someone attack someone else in the video. They might do a punch. Then the other guy does something really cool in retaliation. But don't look at that guy. Instead, look at the guy who punched to begin with. What happened to him? The answer is: He just stood there. As soon as he was done with that punch, he didn't do anything after that. That's not realistic. That's acting.
One more thing... "Force" and "resistance" are two different things. So when I say you need to train with fully resisting partners, I'm not saying your training must involve getting beat up every day. In fact, the opposite is needed. You need a safe way to practice with full resistance so that you can keep coming back day after day and make progress, hopefully while having a lot of fun as well! You increase force as you are capable of doing so safely. That comes gradually.
Arts like Brazilian Jiujitsu and Judo were developed with this concept in mind. They limit the techniques they use in various ways so that they can SAFELY practice at full speed, with full resistance, and even full force (when you get advanced enough). That allows them to keep getting better and better while at the same time minimizing injuries.
Oh, and the weapons? It comes up in reality. You should know your way around knives, sticks, and maybe firearms. That will round your training out. I'll get back to those in a little bit.
Now, what about Taekwondo? Does it teach all of that? The answer is: No.
In Taekwondo, you will learn the free-fighting range only. You will not learn the clinch, nor take-downs, nor the ground fighting. And, you will learn a subset of free-fighting that restricts you to something known as the "long and medium distance" range of free-fighting. That is to say, your goal in Taekwondo is to keep your distance and keep mobile so that your opponent never is able to clinch with you and take you down.
If you ever get clinched and/or taken down to the ground, having only trained in Taekwondo, you will be a fish out of water. You will not know what to do. You will have had no training for those situations. And you will likely lose that fight.
Many Taekwondo proponents, however, would suggest that Taekwondo is all you need for self-defense. They would say you just need to keep your opponents away from you and hit them fast and hard. Do you buy that? If you do, then Taekwondo is fine. If not, then you might want to look elsewhere.
Me personally, I don't buy it. I have a black belt in ITF Taekwondo. It did me very little good when I had to fight for real. I found myself in unfamiliar territory and just froze. This was when I was a brown belt (one before black belt), in my high school years. That encounter was very enlightening, because it told me very quickly that my training wasn't preparing me for realistic self-defense.
My recommendation is to seek out a qualified Gracie Jiujitsu school. Learn their method of fighting. They start out teaching mostly take-downs, ground-fighting, and grappling defenses against punches and kicking. Later on they'll teach more about boxing, kicking, and the clinch. And at some point you might then start taking MMA (mixed martial arts) training, which utilizes everything you learned in Gracie Jiujitsu, but adds more attention to the free-fighting and clinch ranges.
Boxing is good also. Nothing wrong with boxing. But like I said, it's just one range, the free-fighting range. It doesn't go over the other two ranges. But, boxing does train much more realistically in the free-fighting range than Taekwondo does. They don't teach kicks, but they do teach how to punch faster and harder than TKD does, as well as tactics, combos, and defense work that TKD misses. Boxing also covers the scary close distance range of free-fighting, something that TKD doesn't. And if you go on to train in MMA or Gracie Jiujitsu, your boxing skills will fit in perfectly. It's not going to be time wasted, in other words.
Another good one to look at is Muay Thai. Thai boxing is powerful and effective. Taekwondo emphasizes "points", but Muay Thai emphasizes damage, defense, and knock-outs.
Point fighting means that you can kick or punch an opponent somewhere, and it counts as a point even if you just lightly tap it. In Taekwondo, they can hit hard, but they often "slap" or "tap" to make a point, because it means less "winding up" and telegraphing. That translates into faster strikes, but at the expense of power and the ability to hurt your opponent.
In Taekwondo, they even have rules against causing your opponent to bleed or hitting with "excessive" force. So when you train like that all the time, you will tend to optimize for those sports rules. In TKD, that means your punches and kicks will usually connect and with far less force than would occur with Muay Thai or boxing.
And as a side-effect of point sparring, if you only get hit with light force blows, then you're not going to defend quite as strongly. So when you find yourself getting hit "for real", with enough power to knock you out in a single blow, you will probably attempt to block it, and it will partially work, but it will still hit you very hard. You might even lose your balance and fall from the blow. At which point, you're on the ground with no knowledge of ground fighting.
So again, my vote is in favor of Muay Thai and boxing, but more or less against Taekwondo if your goal is realistic self-defense. The Muay Thai and boxing are limited in many ways, but they at least are realistic at what they do and can be combined with Brazilian Jiujitsu, Wrestling, kick-boxing, and MMA. Taekwondo is okay only if you intend to go on to train in Thai boxing, kick-boxing, boxing and/or MMA. That is, again, if your goal is realistic self-defense.
But again, I strongly recommend looking at qualified Gracie Jiujitsu schools first. That will give you the biggest bang for your buck. The time you put in there will be worth it.
Okay, so what about weapons? The knife and stick are two common weapons you might encounter. Firearms, too.
What about Japanese samurai swords? No. How about the 6 foot long staff? No. Nunchuck? No. Kama? No. Sai? No. Etc. All of those ancient weapons that you see in movies? They almost never show up in realistic self-defense situations. You will often see knives. And sticks to a lesser degree, although more often you'll see weapons that take the form of a stick, such as a crowbar, a handbag, a shoe, a baseball bat, etc.
So what martial arts teach knife and stick? And how realistic are they?
The answer is: Lots of martial arts teach these weapons. And while it may look realistic, it's often not. Even Filipino Martial Arts, which excel at the knife and stick, often spend their time learning intricate patterns that do you very little good. Their basics are probably the best of any style out there, but beyond that, it's probably not useful. After the basics, you're better off moving on to something like what the Dog Brothers do.
Or just stick with the basics and realize that even the best at knife fighting often say that they're only slightly better off knowing what they know. In reality, no martial art deals with knives very well. Slashing knives around is often too fast for the human eye to track, and so it's prone to a large degree of error.
You can do better against stick than a knife. But again, most people don't use sticks. And the basic training of Filipino Martial Arts (escrima / kali) should be fine.
That leaves firearms training. Most martial arts don't have anything to say on the subject. You'll occasionally find it discussed in Aikido, Hapkido, classical Jujitsu, and Ninjutsu. But it won't often be realistic.
One of the martial arts with the most realistic firearms defense would be Krav Maga. But my opinion of Krav Maga is that it's not optimal at just about anything else. There are a lot of Krav Maga proponents that spend years training it and really think it's the best. But they're easily tapped (submitted) by Brazilian Jiujitsu white belts. So you can do one of their 3-6 month courses, and I think that would be useful. But my opinion and advice is to don't keep going much longer than that.
And of course, for actually learning to use firearms, you have to attend gun safety courses and get yourself to a firing range. And keep on doing it from time to time. It won't tell you how to defend yourself against guns, however, but it will educate you in the anatomy of guns so that you can recognize how not to handle it when dealing with someone who has a gun.
Okay, that's my personal opinion and advice. Sorry it was so long, but I wanted to give you a complete understanding as I see it. Hope it was useful to you.