I like it all: dense narrative and detailed world building, rigorous exercises in interpersonal relationships and group dynamics and the crunch of min/maxing a character so that every turn is a chance for the tables to be turned and send the baddies running with soiled pants.
Personally I think of myself as the RPG utility player: give me stimulus and I will react to the best of my abilities. I'm a level-headed person and analytical and able to roll with the DM ruling punches. So whether I'm running or playing you can be sure that if I am getting good material I will build on it.
D&D 2e and 4e, no 3 or 3.5. I never learned the 3's an I don't really have any plans to. I've also played some scion though at the end of the day I find few things that beat the good old fantasy genre and d20 system in my mind. Half a year ago I was DMing/playing roughly 3-4 games weekly. While I would love to do that I can't commit the time any more. 1-2 games a week is my max without driving my SO insane.
Personal tastes: mythology, history up until the end of the Enlightenment or so. Japanese, English Civil War, High Fantasy, Historical Fiction and your usual D&D trope materials :P