rossatdi said:
spiritual stuff.
I am naturally very strong. I was looking for something that might fit me
You mentioned boxing, I would go with that. A martial art, most of them anyway, are about agility and balance, more than strength, for example I'm quite a weak (Arms ways anyway) short person, but I guarentee you if you can put someone off balance and apply pressure to a "pressure point" you're going to seriously hurt them.
If you want the best one for real situations, Judo teaches a lot about disarming someone with any kind of weapon. I remember practising with rubber knives and BB guns, again though was more about balance and speed rather than brute force, ofcourse if you can smack the person who's threatening to kill you hard enough to make them unable to injure you in the process then strength is the way.
I havn't read all the replies and I do appologise for that. But for personal fitness, Tai Qi is probably the best... but also the most spititual. If you prefer more agressiveness, but usefulness in situations you may well encounter, Judo with it's disarming properties could be better...
Like you, I have rugby players legs, I'm a winger, and judo doesn't involve much kicking. Ofcourse it has all the usual things you'd see with kicking (My favourite being the double roundhouse

) but it also has a lot of "Spacial awareness" and blocks for punches followed by repostes. It was the only primary self-defense thing I would ever employ. (The... 4th Kata in Judo begins with two kicks, following by sweeping of the floor with your feel (Moving glass out of the way, if you where being attack in an alley or anything... You don't want to land on glass.)
Again, sorry for not reading all the replies. Personal fitness, Tai Qi, but if you want a self-defense that isn't so spiritual... Head for Judo classes.
I just saw something, by the way:
Plus you're going to have to be pretty damn good at kicking to knock over a 200lb guy with a kick. Legs as far as I'm concern are controlling you and your opponent, kicking is for street fighter characters!
Don't underestimate balance... When I was just a second white in Judo, I thought the same. Dummy with one leg, draw you to that side, move the same leg and hit them with the heel. It's really detailed stuff. Ofcourse, you can just pelt them pretty hard too, for example a drop kick, one of them to gut will send you to the ground or atleast stumble you. (Judo has a LOT of fighting on the floor (Several katas devoted to it and indeed a lot of time spent learning ground fighting)Meaning if he'd drop kicked you he could easily get to you again pelt you in the back of the legs.
Sorry if it's a bit long winded, hope this answers your question.