Which PSU should I get?

[Hiscore]

I need to select a PSU for a new build of mine.
I made a thread regarding gpus right here: http://www.tomshardware.com/answers/id-1843740/760-670-7970-280x-gpus-fresh-build.html#11735421

Now, I'm not exactly sure what my power consumption will be, but I am absolutely certain it wont be above 750 and most likely will never pass 550. So I'm trying to settle a dispute between three different PSUs.
The first is this: http://www.newegg.com/Product/Product.aspx?Item=N82E16817139010&nm_mc=EMC-IGNEFL101513&cm_mmc=EMC-IGNEFL101513-_-EMC-101513-Latest-_-PowerSupplies-_-17139010-L0D
I like that it's Corsair, and it has nice wattage, but it's not Platinum like the next one.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817182084

Last is this-suggested by a friend: http://www.newegg.com/Product/Product.aspx?Item=N82E16817139054

Which one is best? They are all very similar prices and I'm not sure if I should get the extra wattage (I was told it wouldn't be as efficient working at lower load and the fans wouldn't go on at lower loads). I was also told that Rosewill isn't a great brand and Corsair has excellent service. Keep in mind that the Rosewill has a SEVEN year warranty on it.

Thanks a lot to everybody who helps out! I really appreciate you spending your time on helping a new person like myself.

 

[nostall]

Either of the Corsairs would be a good choice; the difference in efficiency will never be noticed. The HX has a 7 yr. warranty.
I know nothing about the FORTRESS series of Rosewill, but their CAPSTONE series is made by SuperFlower, one of the best out there.
The HX is 'semi-modular': The main power to the mobo, and the EATX 12V Auxillary power are hardwired to assure the best possible power to that component. This is, IMHO, a real plus.

 

[Hiscore]

Thanks! You've been helpful.

 

[nostall]

You''re very welcome. Tell us about your build when you get it together.
And thanks for joining Tom's and posting.