TKD is a sport... MMA is a sport.. Takedowns are totally impractical unless you are guaranteed a fair one-on-one fight on some matting..
Do you want to learn how to fight, or how to survive? If you want to learn how to fight, go learn kickboxing or some other mindless idiocy and start looking for trouble.. You will win some fights, and that might make you feel good, but eventually you WILL come up against someone who can outfight (or simply shoot) you, and you WILL get hurt...
If you want to learn how to survive, learn something practical and flexible... Many "martial arts" are simply for thugs looking for trouble.. Whatever you choose, make sure you've completely sussed it out before wasting a lot of time and money learning possible bad habits, and make certain that your instructor has a good reputation. And for god's sake just because he's a 26th dan or has trained tournament winners DOESN'T mean he's any good. Tournaments and street fights are like chalk and cheese. A good brawler will hand a grandmaster his teeth and thank him for the good time in most situations.
Chinese styles in general are fast and standup, Japanese styles are more powerful, but also slower, Korean styles normally involve lots of pretty (useless) high kicks, Brazilian styles are generally strong on the floor but not so much when upright, Thai styles were designed to be used in a ring... the list goes on and on..
Look into the heritage of the art you are thinking of dedicating your time to... How/why was it invented? Who used it? Was it a sport, or something else...??