For the Corsairs, I don't see a reason to buy the 550 over the 650 with that 2 dollar difference. The 650 gives you more of pretty much everything except that 5% efficiency. However, if the BlueStorm or that OCZ are gonna do it for me, no need for me to be spending that extra $ unless someone gives me a darn good reason.
Other suggestion in the 50-100$ price range are also very welcome!
2) If u have to buy a new PSU...then go Corsair. The quality of FSP, though decent, is nothing like the quality of the Corsair PSUs and for a $10 difference just go for it. Get the 650 over the 550. They are basically the same unit (both Seasonic OEM) just one has 100 more Watts. The Efficiency is great on both units. Dont use Newegg reviews/specs. Get PRO reviews (jonnyguru.com, Hard OCP, etc.)
And i dont even want to mention the OCZ. In the Hard OCP review it failed horribly. The only good one are the Elite ones.