Depends what your goals are, what you're looking to achieve. I train Muay Thai and in my opinion is by far the greatest, but that's because I like the art of striking. There are many different Martial Arts. Do you prefer striking, or grappling and submission wrestling? Brazilian Jiu Jitsu is another great Martial Art that I'm looking to train when I come back from Thailand.
I have been doing tae kwon do for years. Good for discipline, self defense and it can be a great work out.
obviously karate is my choice .. Not only prepares physical health but also but also the concentration
Ask yourself what are your goals? Fitness Self-discipline Self-defense Competition Social Then look around and go to the club that most closely matches your goals. It does not matter what style. Look for a great instructor that can motivate the class, has good rapport with the students, and where everyone is friendly and helpful. It will be a reflection of the chief instructor there.
Its not necessary that if you are expert in martial arts you can fight against number of people. That is just for your own self defense.
I have been training in Taekwondo for about a year and think it is fantastic! good fitness, self defence and striking you also lurn patterns and drills which i love