I'd say FPS, but I like games most when they combine elements from multiple types. e.g. I like NS because it's both a strategy and FPS game.
I used to play RPG games a lot, but I don't really have the patience for 'em anymore. Action RPGs and the like are okay, but you won't catch me playing the traditional turn-based RPG anymore unless it's a classic (basically any SNES RPG).