AFnord: CRPGs first and foremost
Followed by strategy games and adventure games.
But I'm playing games from most genres
Me too.
First place are cRPGs, specifically those made by Troika, early Bioware, Black Isle. Of that era, that gameplay, that GUI/representation (isometric POV w/lavish detailed 2D backgrounds), and especially, writing. The culmination of the dream started by
Ultima VII.
In second place comes "First Person Sneakers." The
Thief series, naturally, and games that try to take a more cerebral or crafty approach to the standard FPS gameplay, like
System Shock 2,
Call of Cthulhu: Dark Corners of the Earth,
Condemned: Criminal Origins, and hybrid games like
Vampire the Masquerade: Bloodlines, which is really in a league of its own.
Third place comes "Space Sims," i.e. the
Wing Commander franchise games, and
Freelancer. Pity this genre is more or less moribund these days.
I'm not really a strategy games person, despite
Sid Meier's Alpha Centauri being one of my favorite games of all time. Not a big adventure game person either, really, despite my love for
The Longest Journey. I'm actually more attached to development companies than genres, when I think about it.