Well for a start DO NOT BUY THE PS3 VERSION.
Now that that's out of the way.. I have the PS3 version and whilst I know that a lot of people are apparantly having no problems with it, the majority of us are. And they're of the game breaking variety. Stuff like random crashing, crashing due to extremely low frame rate and frequent stuttering due to pop-in issues.
I haven't looked into the Xbox Version very much, but I'd be genuinely surprised if it was in worse shape than the PS3 version. The PS3 version is bad. But hey, if you do buy it for the PS3 maybe you'll be one of the lucky ones who get no problems at all.
Can people like you please stop making things up and try objectivity for once? The majority of PS3 users are NOT having game breaking bugs. The game breaking bugs can be found on all platforms in some form, and they're a MINORITY of cases.
There hasn't been an actual study, as far as I know, into which platform is more stable. The PC is PROBABLY more stable due to the fact that reviewing sites have had multiple employees report that the PC versions have less bugs, but even then, the pooling group is still too small to make any realistically accurate statement. Between 360 and PS3, it's a crap shoot. Even if someone on this forum was obsessed enough to buy the PS3 and 360 versions, they're one case out of hundreds of thousands, if not millions of customers. It'd be like if I picked out three hundred people in the US who had blue eyes and claimed the evidence showed everyone in the US had blue eyes.
The fact is that a minority of 360 users have game breaking bugs or perfect games, a minority of PS3 users have game breaking bugs or perfect games, and the majority of us are dealing with a few freezes and restarts every play through (40-60 hours). Pick the platform you enjoy most. Personally I like PS3 controllers more...