A tough call, actually. The Zalman is based on an FSP Epsilon, although they've modified the pi filtering caps on the secondary side to reduce the ripple on the +12V line that plagued the other Epsilons. The only review that included properly carried out ripple measurements (I think it was an spcr one) showed it as having reduced ripple, although it does still have the same official rating as the Epsilon (200mV, which is greater than the 120mV allowed under spec).
Aside from this the only other major difference is the heatpipe, although its effect is dubious. SilentPCReviews show it as being quite loud.
The actual power difference isn't huge - a total of +12V@42A on the Zalman (although I suspect this is rated quite conservatively) vs the +12V@40A on the Corsair, and the Corsair is rated at 50C vs the 40C rating of the Zalman (so total output would be quite similar). The build quality on the Corsair is somewhat better, and the efficiency slightly so. According to SilentPCReviews, it's also quieter. Looking at the price, it still seems to be $5 cheaper.
Either unit will be sufficient for a single DX10 GPU, although neither will hold up to a multicard DX10 rig.
Keep in mind that the Corsair isn't really a triple rail unit, it has two, at most, but no OCP (so you can load any +12V rail up as much as you want).
All things considered, with your stated requirements - I'll have to say go with the Corsair.
