I prefer the OEM (i.e. Seasonic) that Corsair uses for the now discontinued CMPSU-750TXV2 that you've linked to.
OCZ uses an obscure OEM, Great Wall, for their OCZ-ZX850W.
Both models have a 5 Year warranty.
If you don't have much room in your computer case to hide the extra unused cables for the Corsair CMPSU-750TXV2 then get the OCZ-ZX850W.