They are both very high quality units that I would trust. Both are manufactured by seasonic with the x650 being their newest and most efficient design as it is 80 plus gold certified. I would say get the seasonic if you're going to use a single graphics card the corsair if you plan on using dual cards. Either way you'll be very happy with your choice.
The Corsair HX 750 is from CWT. Anyway, I agree with you.