I'd prolly stick with the evga gtx 670 because its from evga. I've heard great things about the msi one though with overclocking.
I wouldn't go for sli gtx 660 ti, it would be much better to go with cf 7950/7970 or sli gtx 670.
Also, this all depends on how much you are willing to spend.
P.S. I have an evga gtx 670 and its performed marvelously and OC'd pretty well.
How Hot does it run? and have you OC'd with stock cooler or aftermarket?
Thank You for your reply