well like they said man, all of em would cut it technically. But out of all the ones you listed OCZ is superior is what they are saying and I agree. From all the articles I've read the OCZ Platinum edition performed better than Corsair XMS in performance, overclockability, and of course benches. Those OCZ will kick major butt.
BUT ALSO....check these out:
They are rated at DDR400 - 2-2-2-5 and DDR533 - 3-4-4-8
Now of course 3-4-4-8 timings suck compared to the OCZ 4200, BUT that's just what the company guarantees it at. They can actually obtain tighter timings.
It's like $150 cheaper, unless you just really don't care, and you should be able to hit those 2.5-3-3-8 timings with some luck of course
But that's more of a gamble type option whereas the OCZ will definitely be delivered to you with those timings and speed.
But really at this point you're getting major high performance RAM so any of em would cut it