I would use the antec personally. Mainly because manufacturers like to overshoot their PSU ratings and that 650 is rated for 456w on the 12v rail and thats... a little low. Plus I haven't heard to many glowing recommendations for ULTRA.
I was thinking that too, but it has amazing reviews...
Also dont most graphics cards take 2 pci-e power cables? Both psu only has a total of 2 so you are going to need some molex adapters as well