The 7970 is faster and cheaper, and Eyefinity is better than Surround. Go with the 7970.
As to the eyefinity setup, I've read that the AMD cards are very particular as to what output you use. I already own a DP to HDMI adapter and a DVI to HDMI cable, but I've heard that Eyefinity prefers all connections to be DVI. Would I have to buy a different set of adapters just to get Eyefinity to work properly?