I did a season of folk wrestling in high school. This was about 5-6 years ago. I'm trying to diet and exercise properly to reach my low body fat goal. Also, I want to learn some basic self defense. I am a short male (5'4") and weight about 170 lbs. I want to be able to be prepared against any kind of oppenent. My biggest worry is the taller opponents with long arm reach. What would be the best martial art to go into between wrestling (further into), boxing, and jui jitsu? I have a slight preference in learning boxing of the three.
You are looking for a unicorn there. No martial art whatsoever is able to do that. There is no ultimate fighting art. That said, most martial arts (McDojo excluded) can give you an edge in self defence. It will shift the odds in your favour which is a good thing.
However, self defence is not just about fighting. It is about observation, preparation, awareness, and many other things. No Nonsense Self Defense is a good place to start if you want to learn more.
As to which martial art is best between wrestling, boxing, and jujitsu. It is like comparing apples, oranges, and mangos. None of them is better than any other. It depends on your personal tastes, who is teaching, where the classes are, and where do you have the more fun!that said, both wrestling and boxing have a fairly narrow focus: one opponent, heavily sport based, and well structured fights. Jujitsu tends to have a wider focus. Then again, Jujitsu is a catch all term for most (if not all) Japanese martial arts before the Meiji restoration. So, "learning jujitsu" sounds odd to me.
"I'm trying to diet and exercise properly to reach my low body fat goal. (..)"
That said, boxing is the way to go. The workout is quite intense, because you need to build stamina in order to box properly.
"Also, I want to learn some basic self defense"
For self defense, i would include Brazilian Jiu-Jitsu as well, since it has proven its effectiveness (see MMA). But let's talk about boxing:
It teaches you how to take a hit and not become desperate. No martial art makes you untouchable, and even when you have better technique you can still be hit. When i spar with guys way above my level, i can still land a few punches.
Since you do a lot of sparring, you have something like a combat simulation. Of course, under rules and in a controlled environment, but one thing is to train with your partner "helping" you to execute the move, another is when he really wants to hit you. =)
I can talk about a lot more, but this text summarizes better: The martial art of boxing
There is no magic against "any kind of opponent," because your opponents are so potentially varied. Some are armed; others not. Some are individuals; others are groups or gangs. Some are simply angry; others are (pardon the now-obsolete psychological phrasing) psychopaths. Some are your drunk uncle Eddie, who you don't want to hurt, but you can't have him putting his hands on everyone at the family BBQ. Different weight classes, different weapons, different intentions--the variations are endless.
Pretty much any martial art will help train you in cardio fitness, in balance, in using your weight and strength more efficiently. But some--Western fencing, Kyūdō (Japanese archery), Iaido (the drawing and use of Japanese swords), or Kendo (Japanese swordsmanship with bamboo swords and armor) just to name names--however lovely and historical as arts, are simply not practical fight training for modern people. Similarly, in most Western countries, any art that assumes you will be always armed (e.g. Eskrima, Arnis and Kali) are just not practical. In most places you cannot carry bladed weapons. Even if you could/did, and then used them, you'd probably go to jail for slicing your opponent up in the ways they train/suggest.
For self-defense, I personally prefer training in arts that emphasize the the punching, trapping, and controlling range (arms-length or closer to your opponent) rather than kicking or grappling range. So, Japanese Jujutsu or its American Small-Circle derivative, say, rather than Taekwondo, wrestling, or BJJ. Some karate schools incorporate controls and throws in with striking moves, which is a nice mix. Some kickboxing or sport combat instructors who are savvy to MMA and BJJ teach similarly fluid styles that combine striking, control, and joint-locks. Any of these are preferable to the highly-refined, stylized arts.
There are also some martial arts that are specifically "combat engineered": simplified and refined, removing traditional flourishes and sport-fighting rules to focus only on defensive fighting. They're more "martial skills" than "martial arts." Systema and Krav Maga are often cited, though American Small-Circle Jujitsu, Combat Hapkido, and other variants are out there.
You've had wrestling experience, so why not focus on boxing, kickboxing, or jujutsu to extend your range/set of techniques? I know when I added kickboxing and Small Circle Jujitsu techniques to my bag of tricks (previously kung fu, Judo, and Eskrima), I felt enormously more capable in defensive situations.
Sardathrion makes an excellent suggestion about techniques like "No Defense Self Defense." They extend your awareness, posture, voice, and presentation, and are really the most effective defense you have. If you're looking for true self-defense training, it's not a matter of just "choosing a martial art." The "real world self defense" systems that incorporate awareness, the use of your voice (e.g. Verbal Judo), under-high-stress adrenaline dumps, and truly defense-focused techniques are worth seeking out. Rory Miller's Facing Violence: Preparing for the Unexpected is a good place to start to bridge the gap between "martial arts," sport fighting, and real-world violence dynamics and responses.
Here is a recent podcast on this topic: PREVAIL Podcast #3: Self Defense and the Martial Arts. (Full disclosure: I am one of the participants.)
I've been studying martial arts going on 2+ years and I have to say that a Good teacher is one of the most important thing you can find. Some things I would look for are these.
Depends on what place you are. If you are any where near the Erle Montaigue System Instructor. Hundred times better and practical than McDojos.
Some videos to gets the flavoured (selected to give overview), see if it spikes interest. :)