Well until I get my PS3 which won't be for a while far as I can tell it'll be all 360. Still I'm inclined to get the best version of the game regardless of console. I mean there are so many variables, like controls, extras, online, hardware specific game features, community, friends, etc.
I got Fifa on Gamecube cause I liked how the pass button was A and it made the game play better. Not to mention faster loading. I like Metal Gear on PS2 cause the game is designed around that controller, I own Subsistence and still prefer the game on PS2. I got PoP Sands of Time for Xbox cause there was supposed to be DLC. I got Halo PC for the extra maps and online play. PS2 only had two controller ports too. I just get what I think is the best version, sometimes that means buying a game twice.
A good current example is I heard the PS3 version of Virtua Tennis 3 isn't online, don't know if it's true but on 360 it is. I hate the PS3 controller for FPS but feel like motion control will make some ports better. Still there's lead sku, and timed exclusivity which are all factors and if you're a multiconsole owner you weigh all those variables and walk away happy.