GTX 460SLI or GTX 560 TI SLI

overall the GTX 460 is 22% slower than a GTX 560 http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_5...

you just have to decide if the performance gain is worth 120 bucks.

Definitly 560 (Dx11+faster+better scaling in SLI+Better temps+lower noice).

Its more expensive yes, but Id never advice you to get something getting "outdated".

460 will hold for 1 year more probably, but not that much longer.
Also note that so far DX12 oficiall resease is 2013 (1 year after worlds end  ), and in 2 years i guess you will be able to update for new GPU

^460s also have Dx11  .*no offense* but imo 560s would be much better