Fighting Games: I tend to pick slower characters that are built around timing. In both SSBM and SSBB I'm a huge fan of bowser, and all my friends hate it when I pick him because I make him do the impossible (re:win) all the time. When I don't pick him, I tend to go for zone manipulators, or those who can easily move in and out of zones, or create new ones on the fly.
It's not even so much that he's slow, it's that so many people suck with him that I pick him. It's like I enjoy beating people up with the 'worst' character available. It all centers on my ability to read the opponent and having insanely good timing.
Racing games: I love traction, so in the past the characters with the best control win my heart. More recently though, the fast but barely controllable guys have been winning my heart.
Strategy: I usually go for a rounded mix, but if I know there's a weakness present in the opponent, I will exploit it. I'm famous for bunker busting. Outside of that, I'm a bit slow in reaction times because I don't always see what's going on. I'm horrid at watching mini-maps (just ask the HoN folk)