It really depends. If you want self defense, Krav Maga would be the ideal. If you are training for mma, brazillian jujitsu and wrestling are the keys. If you want to look like a badass at home in the mirror, kung fu is pretty cool looking. It depends.
Brazilian Capoeira...Provides an attacking form, Ginga... A dancing form, and an esoteric form for relaxation...
I learned the forms years ago in Berkeley...Its been a part of my daily regimen ever since...At 73 I still play to a 4 handicap in golf, play competitive basketball in the local gym, and remain flexible enough to still make moves on my wife...That last is a benefit worth all the years of practice.
Maybe best to learn something as a base like Tai Chi... so the old ladies can't deck ya mate!
But all joking aside it depends what you are trying to achieve - most exponents don't restrict themselves to a single discipline, they master one and then explore the 1000s of other fighting or defensive techniques that have developed from that very reason.
The 'True' arts remain the same in their purest forms - but since things like cage fighting etc. all styles have evolved to suit the personal characteristics of the exponents!
I learned Judo and then expanded into Kempo and dabbled with Kendo, Thai Boxing and Aikido. Where do you start, where do you stop? Once you have mastered certain things you want to explore other styles and techniques.
I doubt that, my friend...Bobby Jones once said golf is a game played on a 5 inch course...the distance between your ears...The same would apply to life...it's what is in your head that counts, not what your body is showing...
I have been privileged to study the martial arts since age 10 I'm 57 and last year, when my Grandmaster passed away I inherited the 10th Dan. I wont tell you the style as it means nothing. I think over the years I have seen and been involved with all major martial arts. Something you need to know about which style is best reflects the simple adage, "It ain't the arrow, its the Indian."