According to hardocp the Powercolor is a good overclocker and can beat reference 7950.Yeah get the Powercolor. What are the cooling solutions like? You might not be able to overclock much with the Powercolor.
raghu78 says the Sapphire has better cooling, otherwise they are identical. Sapphire has their 2 fan cooling and Powercolor only has 1 fan.
I like the look of the Sapphire but it's much more expensive.