I am a relative newcomer to tabletop roleplaying, having started in 2009 by running D&D for a group of co-workers. I still prefer to serve as GM, though I have no qualms about playing.
My personal preference - both as GM and player - is for investigation-based games (Pelgrane Press' GUMSHOE line being my favorite RPG series) and sandbox games (I find all of Sine Nomine's offerings to be absolutely fantastic).