You haven't listed priorities so much as requirements. So I'll treat them as all more or less equal in priority. Though, it might be helpful if you were to indicate which were more important and which were just something nice to have. That can often give you a better result.
Your requirements for martial art are:
- Must have relaxing, meditative aspects.
- Must be good for self-defense.
- Must be good for weight loss and physical fitness.
Meditation / Relaxation:
I'm just going to go out on a limb and say every martial art I've ever encountered has been good at taking my mind off of my day to day worries and putting me in the moment. They all provided a mental break, causing me to forget about anything else going on outside of class.
The reason for that is that martial arts demand you pay attention to what's going on right there and then. If you don't, you get punched in the face. Or your movement will be sloppy, and you'll be forced to make quick corrections which will require 100% of your brain focused on the task at hand.
But you may be wanting something even deeper than that. There are martial arts that explicitly engage in meditation practice. While often not officially part of the curriculum, it is generally included in most Taiji, Xing-Yi, Bagua, and Aikido schools. These are "internal" martial arts, but even external martial arts schools such as kung-fu schools tend do it.
Personally, I wouldn't make this explicit meditation practice a requirement if I were you. You can meditate on your own before or after class. There's very little a martial arts instructor typically teaches about it. They often just have you clear your mind and concentrate on breathing while sitting down on the floor. It's designed to clear your thoughts and get you more in the moment. And it usually only lasts about 5 minutes.
So my advice is that you'd be better off reading books and getting videos about it and decide on your own what to do and how to do it. There are even workshops and seminars that you can go to. Yoga places tend to teach it as part of their normal class routine, and they often have workshops devoted to it.
You can go to Zen Buddhist temples, and they often have an introductory class in meditation. They're some of the best people from which to learn, in my opinion. It's because it's actually a fundamental part of what they do. They have different levels of meditation from beginner to advanced, and they will instruct you more deeply than your typical strip-mall martial art class will.
The other thing to realize is that you're paying for this. If a martial arts school is taking time out of the class to do something, you're paying for it. You have to ask if you're getting your money's worth. Is it the best use of expensive class time to take however many minutes out just to meditate? Or would it be better that you meditate before and after class on your own free time?
That's a question only you can decide.
You mentioned you wanted "reactive" self-defense. I guess it means you don't want something that's active and combative like MMA or Muay Thai would be.
What people usually think of as "self-defense" training are techniques that can let you escape a bad situation. Like you might learn a self-defense technique that will break someone's bear-hug hold. And when they release you from that bear-hug, you're supposed to just punch them in the face or kick them in the groin and run.
That's the traditional interpretation of "self-defense". They're quick techniques to deal with specific and common scenarios in order to let you stop the attack from happening and get away unharmed.
The only problem is that these don't usually work very reliably. And that's because when the attacker feels you breaking his bear-hug, he might switch to just tackling you to the ground. Or maybe he'll change to a side-choke instead. Etc.
And if the bear-hug release technique actually did work for you, maybe that kick to the groin you followed up with didn't result in him dropping to his knees in agony like you learned in class. Now you're face to face with a very angry guy whom you just kicked in his testicles. Are you ready for what comes next?
In these traditional forms of self-defense classes, an attacker that fights back isn't part of their model. To them, that's "fighting", and it's not the same.
My point is, you might want to reconsider wanting to learn "reactive" self-defense only, rather than also learning how to fight. Because, if you learn how to fight, the self-defense is just the cherry on top. It becomes a small part of your overall defense, in other words. The fighting skill backs it up and allows it to work, if it's going to work at all.
To clarify, a self-defense technique might work for the first two seconds of the fight. After that, you're fighting. And it's kind of wishful thinking that your self-defense technique will work just like it did in class on a partner that let you do it to him, allowing you to just run away unscathed after it worked perfectly.
So how do you recognize martial arts that train people how to fight reliably? Which martial arts are better at it?
What we've learned about martial arts in the past two decades is that what matters most is how you train, not what you train. Style and techniques are unimportant. So long as your training involves sparring against "live" and "non-compliant" partners, the techniques you use and how you use them will be honed to fit that situation. And that situation, by the way, most closely approximates a real fight.
What does it mean to have a "live" opponent? It means that your partner isn't a robot. He's not going to tell you what he's going to do. He gets to decide that. And he doesn't stop once he completes what he was doing. He keeps going, reacting to what you're doing. He's alive.
What does it mean to have a "non-compliant" partner? It means that your partner is actively resisting everything you do. He's not letting you do stuff to him. He's trying to win against you. He is doing what he can to stop you from doing whatever you're trying to do.
So long as you have live and non-compliant partners, you have the basic recipe for success.
And I would add that competence in fighting requires training in all ranges of fighting. That includes free-fighting, the clinch, and the ground. In free-fighting, you and your opponent(s) are standing, free to move around, because nobody has a hold on anyone else. In the clinch, you're both standing, but someone has a hold on the other. You're not entirely free to move. And on the ground, you're either on your back, on your stomach, on top of him, him on top of you, beside your opponent, etc.
When you're comfortable in all 3 ranges of fighting, you won't freeze up in a fight. Everything will feel familiar to you. And your training will take over.
Martial arts that practice this way and which have a proven track record for producing the best fighters are martial arts like MMA, Brazilian Jiu Jitsu, Muay Thai, Wrestling, Judo, Boxing, Kickboxing, and Sambo.
Of those, the martial arts that also teach self-defense techniques (similar to classical Japanese jujitsu) are styles like Gracie Jiu Jitsu, most Brazilian Jiu Jitsu schools that don't specialize in sport fighting only, and some forms of Wrestling.
There may be others. But there won't be many others. So that greatly reduces your pool of martial arts if you want to learn to fight in addition to learning self-defense.
If you're just interested in self-defense techniques in isolation without learning the full fighting game, you've got a lot more choices available to you. Such as: Classical Japanese jujitsu, Aikido, Kung-fu, Karate, Bujinkan Ninjutsu, Hapkido, Krav Maga, and so on.
Exercise and Fitness
A lot of study has gone into how to lose weight. The main conclusions are: Do cardiovascular exercise the most to burn more calories. Strength training is helpful for retaining muscle while losing fat, but it's not going to burn more calories and therefore more fat than cardio exercise will. Weigh yourself frequently. And lastly, control how much you eat on a daily basis.
The good news is that a lot of martial arts are highly active. For example, Taekwondo, Muay Thai, BJJ, Wrestling, Boxing, Wushu, and Karate.
On the other hand, there are some martial arts that don't do a lot with cardio. And you can see it in their students. Their students will be overweight or out of shape, yet they'll be black belts. It's okay if some black belts are overweight, but if you're seeing a trend at that school, then that's something you may want to avoid.
I think this is something you're going to have to shop around for. You need to visit some of the schools near you and see what they do.
Everyone will have their own opinions about what you should do. It's going to be subjective. But based on the requirements you've given, my advice is to find a Gracie Jiu Jitsu school near you and take an introductory class, or a week of classes.
Gracie Jiu Jitsu will really make you work hard physically. It will burn fat and give you strength.
About the only thing more intense for you might be MMA or Muay Thai training. But you said you wanted "reactive" self-defense, which I interpret as being something akin to classical Japanese jujitsu. Both MMA and Muay Thai don't generally provide that training. But Gracie Jiu Jitsu does.
By the way, on the subject of classical self-defense, this is something that a lot of Brazilian Jiu Jitsu schools don't teach. But it is part of the curriculum of Gracie Jiu Jitsu. The Gracie system makes sure not to teach the sport aspect until after or around blue belt. Until then, it's all for fighting and self-defense. Whereas, other BJJ schools may have a different curriculum. You have to ask.
And Gracie Jiu Jitsu actually will teach you how to fight, in addition to the self-defense training. MMA just teaches you how to fight, but won't give you much in the way of classical self-defense training. And Muay Thai teaches you a more limited range of fighting than MMA would while also not teaching classical self-defense.
As for the relaxation and meditative aspects, I think some Gracie Jiu Jitsu schools incorporate it into their training, but not most from my experience. But like I said, you can meditate on your own before and after class. And it may not matter, because any martial art will be able to take your mind off of your daily life, like a little vacation for your mind.
If meditation is very important to you, then you should be looking at an internal martial art like Xing-Yi, I think. The only problem with that is that those arts don't generally burn much fat. And they don't do a good job of teaching classical self-defense. Or fighting for that matter.
But assuming you did want to do an internal art, my recommendation is to do Bagua, Xing-Yi, or 5 Ancestor's Fist kung-fu, to name a few. Most of those schools will teach some classical self-defense, albeit a small amount. Most will involve some meditation, sometimes quite a lot. And unlike Taiji, they generally move quickly rather than slowly, which will allow you to burn more calories. They won't burn nearly as many calories and get you as fit as something like BJJ, Muay Thai, or MMA.
If classical self-defense was the most important thing for you, I'd say try Krav Maga. You'll get a moderate amount of exercise from it and will burn some calories. They might even have a supplementary "Cardio Krav Maga" class which you can take in addition to the normal class. And it almost certainly wouldn't give you any meditation practice.
There are some forms of Japanese jujitsu that do involve meditation practice. And it's pretty much all self-defense there. But again, not much cardio.
You said you did Wrestling and some Boxing. That will work well with either Gracie Jiu Jitsu or MMA. You won't have to unlearn things. Wrestling and Boxing are key skills incorporated in MMA training these days, by the way.
You said you had an interest in Wing Chun kung-fu. But it contradicts the requirement for something that helps you lose weight. It's a fairly stationary style, with relatively less leg movement compared with other styles. It does move the arms a lot, but if you're looking for something that burns the most calories, then you want a full-body workout which includes the legs, arms, and torso.
Wing Chun does have a lot of meditative aspects. And it might qualify as "reactive" self-defense, if you mean that you just want your body to react without thinking about it. Part of its skill set is arm sensitivity. Instead of seeing the motion and reacting to it visually, you make connection with your arms and sense the motion. That can cut down on your reaction time.
But Wing Chun doesn't generally offer classical self-defense. It's a fighting system. And as a fighting system, it may not be reliable due to the fact, like I mentioned above, that it doesn't generally train with non-compliant partners, liveness, and resistance while allowing all 3 ranges of fighting. It wasn't really meant as a street fighting style. It was designed only as a counter to the particular styles of kung-fu that were around in the region it was created. Some Wing Chun schools try to close that hole with varying success. For example, Leung Ting's Wing Tsun.
You can read more about my thoughts on Wing Chun here:
Defence against Wing Chun
My only other advice besides finding a Gracie Jiu Jitsu school near you is if you can find one that has some students that are heavy and tall also. And this is because you might learn faster if you didn't have as much weight advantage over some people in the class.
In grappling, weight definitely makes it easier for you to win. The smaller, lighter students are the ones who have to learn the proper way to do things from day one. They pay very close attention to detail, because they need to. But heavier weight people can often get away with being less skilled. At least for a while and against similarly ranked students.
But that is not super important. It's more important to find a good teacher than finding a school with one or two big students in it. And any BJJ school is going to put you through a very intense workout.
One other thing. If you're trying to decide between Gracie Jiu Jitsu and MMA, consider your joint health also. Being 330 pounds means you probably want a low impact exercise for now, at least until you lose the weight. MMA is high impact. Gracie Jiu Jitsu is low impact.
So I'm sticking with my recommendation: Gracie Jiu Jitsu.
Hope that helps!