Since no prices were given I think you would use tomshardware.com to get benchmarks on the GPUs and pick the winner.

However I still like this now under 1K Haswell build.
http://www.pcworld.com/article/2040319/build-the-ultimate-intel-haswell-pc-for-under-1000.html

The CPU is rarely the bottleneck in games. I'm sure you've read this:
"Our tests demonstrate fairly little difference between a $225 LGA 1155 Core i5-2500K and a $1000 LGA 2011 Core i7-3960X, even when three-way graphics card configurations are involved. It turns out that memory bandwidth and PCIe throughput don't hold back the performance of existing Sandy Bridge-based machines. "
http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-4.html

Bob