I was going to get the Corsair TX 650W but now the Antec 750W is on sale, putting them both at about $75, and $50 after rebate. Now I know I won't need that much power unless I crossfire in the future (I will be using a 7970 and an i5-3570k, both overclocked), but if they are the same price, I should get the 750W UNLESS the Corsair is better in another aspect. I have heard Corsair is very reputable for PSU's.
The corsair 650tx is seasonic which is actually the same base design as that xfx. It doesn't have to be seasonic to be good. The antec would be better simply because you can cf 7970. I would not cf 7970 on a 650w psu no matter if it was tier 1. It has a tdp of 250w so you would be over 500w. Not something you want to do on a 650w.
i was going by this: http://www.realhardtechx.com/index_archivos/Page447.htm
and looking closer one model is seasonic and the other is channel well. sorry i got mixed up for a minute.
though it is highly unlikely the card(s) will hit its TDP; gaming power consumption is ~200 watts on the card (of course depending on the model)
to be honest the only thing i think is less likely then the card hitting 250 watts is the OP actually getting a second one unless they are saving funds towards that now along with another monitor; because gaming @1080 with 7970 Xfire is the definition of overkill