The OCZ ZS series is not modular, I assume C12Friedman is thinking of the ZT series.
OCZ ZS 750W has a quieter fan.
Corsair TX750 V2 has a longer warranty (5yrs vs 3yrs).
The OCZ ZS 750W is good enough that if you want to save money then it is a valid choice.
Do you really need a 750W power supply? What system are you going to be using with this PSU?