I did buy a 660 Ti, last month which i'm happy with. It wasn't the "best" choise though. I prefer Nvidia to Radeon.
They're better with updating their drivers, and makes it overall easier for customers, and i don't mind paying a few euro more for that.
They also work better for linux, which is something that matters to me, but radeon is best price/performance-wise for the time being, as far as i know.
Darn. i can't post links.
Go to
tomshardware.com and search for Best Graphics Cards For The Money: October 2012
This is a great place to get some good, trustworthy idea of what you want. I havn't even read it for this month, but they give the 2-3 best cards for all priceranges, varying from very low to the higherst and say what's best performancewise.
Happy reading