evga g3 or cosair rm? and is 550w enough

[freebooter]

I am thinking of getting a new psu to replace my old corsair builder. My current one is 500w iirc. my current system is just an i3, 480 gpu, one ssd and one hd. I may look for 2nd hand i5 to upgrade the cpu. looking into the future I can't see myself going beyond mid level in either cpu or gpu. So the first question is do you think 550w is enough for a mid level single gpu machine?

Secondly the two models I am looking at are the evga g3 and the corsair rm. The evga looks as if it may be slightly better quality but the rm also gets good reviews and has a significantly longer warranty, 10 years instead of 7 for the evga.

Any thoughts?

 

[freebooter]

Sorry it was the RMx I meant. My gut feeling is the evga but that extra warranty with the corsair is tempting as it also gets excellent reviews. The evga is a bit cheaper though.