The main differentiators to me are how good a game looks on a certain platform, how easily it can be controlled using a console controller vs mouse and keyboard, how often I think I might start the game and how long I might play it in a single sitting. I also check community support (modding).
For example, 11-11-11 TES:Skyrim will be released.
Since the scenery and stuff is likely to be much better looking on my pc, I favor the pc version.
However, I will probably play it for long durations, so my couch (and console) win here.
Controler-wise it will be hard to tell without playing the game. However I found TES:Oblivion playable with both mouse/keyboard and controller, so nobody wins there.
The big winner here is the modding community. Since modding will most likely not be supported on the consoles, there is only one logical choice to make (for me), buy the game for the pc.
Other factors to consider might be the release date, availability of DLC, price, DRM and perhaps even portability (i.e. gaming on a laptop).
Cheating is not so much a concern since when a game supports it, it most likely supports it on all platforms. A notable exception is of course cheating through modding which is a pc only affair.
As you can see, all decisions are strictly personal and depending on your circumstances. If your pc is near its retirement, the graphics argument could change in favor of the console. And while my couch is very comfortable, yours might not be.