Depends what you want. If you are running a dual card nVidia setup, a 750i board would be the best choice (brilliant, just like the 650i). Otherwise, the ultra expensive 790i is really the only way to go, as the 780i boards are just like the 680i boards.
For ATI setups, Asus' P5Q Pro is great. If you are running a dual card ATI setup, then the X38/X48 boards would be the best route.