Having played all 3 on the PS3, I have to say 2012 hands down. Working your way up to the top tier teams is so satasifying, the handling is imo the best out of the 3, not too grippy, nor lack of grip, and you know when you're oversteering, unlike in 2010.
The handling in 2012 is the best out of the 3. The ai in 3 is the best imo as well. They're not robots, but they dont crash themselves every race, it's right in the middle.