Well, I bought a EVGA 8800 GT, it was DoA, then I RMA'ed it and bought a BFG 8800 GT, worked wonderful.
For a GTX280 I bought EVGA again. My GTX280 died, earlier this year, thankfully it was still under the warranty. However, obviously, the 280 isn't in production anymore, and so they send me a GTX470 to replace it...
more VRAM, and in alot of games, at least 40% faster. It even takes up less power, haha. Very satisfied with EVGA for that alone, and will probably go with them again just due to that!
Not owned anything Corsair, but I have owned two Antec PSU's, both good, and this crappy BFG PSU. So when I was looking to build my new 2500K rig; I was looking for Corsair, which I used in my cousins case. Great PSU, loved the design, finish, and performance.
Seasonic looks nice, as you said, just the same PSU's really. Enermax looks nice, but they don't have a 750w PSU, which I want, to fit my needs. Now, I don't plan to SLI, and your own PSU calc said for my new system I'll need about 525 watts since of course I plan to OC the heck out of that 2500K. But what if I do ever want to SLi? So yeah, keeping room in there for another. Your calculator says I'd be skirting the 750w line. Now I dunno how accurate that is, but hmm...cutting it close at that rate. Add in capacitor aging...
I may get a 1000w PSU, even for the hells of it...but I do not know, honestly. I feel 1000w is wasted.
I need your wisdom, o Mighty PSU God Reviewer.