Asus and HIS are both solid brands, powercolor is seen to be a bit more of a budget brand by most. If prices are similar get either the Asus or HIS. If the prices are varied get the cheapest of the lot
For the $ the MSI Twin Frozr is where I would put my money right now. It's $50 cheaper than the HIS IceQ and $70 cheaper than the Asus DCII. Both of which are factory clocked, jump to the factory overclocked version of these and you looking at $80 more for the HIS IceQ Turbo and $90 more for the Asus DCII Top. Now you are in GTX 670 territory $$ wise. At just $310 after rebate the MSI Twin Frozr 7950 seems like the best overall bang for your buck at most any price point.
PS, I may have just talked myself into getting one too LOL