Currently using a 460GTX 1GB but looking for an upgrade have eye'd the 560TI 448, but with the newer cards coming and I'm wanting the card to run Diablo 3, and other games at near maxed settings. The budget I've got the GPU was trying to keep it within $250.
Current System using:
460GTX
Intel i5 750 @ Stock Settings
Gigabyte GA-P55-USB3
8GB GSkill DDR3
Corsair 850HX
Corsair 800D
Acer H233H @ 1920 x 1080
TBH, 250$ isn't going to get you much better than a gtx 460 until a 650/660 come out. I would hold on to that money and save up more. Get 250$ more for a 680, and it would be the best investment of your life.