Well, as far as I can tell, the 680i isn't even available on Newegg anymore, and the ASUS 750i isn't $20 more than a 680i board.
And if two boards are the same price and have the same advantages/disadvantages, wouldn't you pick the one that has PCI-E 2.0 support over the one with PCI-E 1.0a/1.1 support?