Muharhar! Lets rock! I've made Judo and Shotokan years ago, but my full contact sport was fights in real life.
So I like K1, but my most favorite martial art is sumo. Don't laugh, they aren't so fuckin' fast and if u see their muscles - soooo coool! Sadly the TV doesn't show frequently this sport and my favorite Takanohana retired while before.
btw: Muai Thai is such a bonebreaking stuff, some pplz I knew has many injuries therefrom. However the power is impressive: The are not really heavy, but hit the other and knock him out!