7 Ultimate 64 on my personal system, 8 on my mother in laws comp. I cannot stand 8 based on the fact that I had to spen a bunch of time just getting rid of the metro screen and adding back a start menu. I use both almost daily and really prefer 7 especially from a professional viewpoint, I know my windows shortcuts and am just used to 7.
My gaming rig: ASUS G73JW: I7 740qm, 8 gigs ddr3, Nvidia Geforce 460m. I like single player games. Nothing is quite as enjoyable as playing with myself.
Windows 8 Pro, got it during the $40 promo. I'm quite pleased with it, quite a few improvements. My only beef is the awkwardness of switching between "Metro" apps and regular apps, although you can get around that using Alt+Tab.