which would you prefer and why? also, what is the main thing to look for when comparing specifications for cpu's?
Personally I'd go for the i7 purely for power consumption reasons:-
"The more critical factor is also the more alarming aspect: the rumors of a 220W TDP have proven true. That explains why these parts will target system integrators first, and the FX-9000 series also earns the distinction of having a higher TDP, but it also raises some serious concerns. With proper cooling, there's little doubt that you can run a Vishera core at 5.0GHz for extended periods of time, but 220W is a massive amount of power to draw for just a CPU.
To put things in perspective, the highest TDP part ever released by AMD prior to the FX-9000 series is the 140W TDP Phenom II X4 965 BE. For Intel, the vast majority of their chips have been under 130W, but a few chips (e.g. Core 2 Extreme QX9775, Core i7-3970X, and most of the Xeon 7100 series PPGA604 parts back at the end of the NetBurst era) managed to go above and beyond and hit 150W TDPs. So we're basically looking at a 76% increase in TDP relative to the FX-8350 to get a 19% increase in maximum clock speed." http://www.anandtech.com/show/7066/amd-announces-fx9590...
AMD desperately need better IPC / architecture to compete with Intel just as much at performance/watt than just "performance at any cost".