I have a decent PC and a console, both in my living room hooked up to my TV. Best of both worlds really. It's just horses for courses imo, some games i'll go for on the console, others i'll go for on the PC.
I guess there are various reasons why i might choose to play on one rather than the other:
1.
Fairly obvious one this - the game is only available on console or on PC. If i wanna play Fable II it's gonna be on the Xbox. If i wanna play Stalker it's got to be on the pc.
2.
It's available on both formats, but maybe the pc version is actually inferior in some way. For example Pro Evo - yes you can mod it on PC and what not, but i just don't find it controls as well. Just something not quite as responsive on PC compared to on the Xbox. So that one thing would outweigh the positives of the PC experience, and i'd plump for the Xbox version.
3.
It's available on all formats but the PC is a better experience in some way. Yeah, it's an old game, but the one that springs to mind right now is GTA: San Andreas which i'm currently re-playing. It's a way better experience on the PC on a big tv, with a gamepad hooked up. Graphics are miles better (particularly the draw distance, which makes a huge difference) and you can use your own music etc.
4.
It's available on both PC and console but i'll want to mod the game in some way. Fallout is the obvious recent one here for me. It's just a no brainer to me that i'll get it on PC. Better gfx + just masses of mods available. I'm really liking the fact that we are now seeing support for gamepads that enable you to control a pc game exactly as you would the console version - and with no setup involved either.Means i can sit on my couch with an Xbox 360 gamepad playing Fallout3 on the pc with all the great mods and the superior gfx. That's just ideal to me.