Corsair is the better brand and actually is more powerful than the OCZ! I run the Corsair CMPSU-850TX model and I couldn't be happier (unless I had the HZ version )
As for the ability to Crossfire down the road, we need to know what your GPU is to determine if either are capable of running it in Crossfire. Neither will handle two 5850's or higher but both will handle 5770's or lower
It would be two 5770s. I actually have the Corsair in my system, which I just built, and my friend wants me to build him a duplicate of my system, but he was wondering if he could save money somewhere. I figured that having a modular PSU might be a better route anyway since my PSU's extra power cords took up so much space in my system.