If you are interested in playing with your PC more than playing on your PC, it seems to me that AMD CPUs are a little more interesting to "tweak," although that probably depends a lot on the board.
If you are interested in maximum performance for games played on your PC, Intel wins. It isn't by a huge margin (especially since the graphics card is typically more important than the CPU for games), but with very few [non-gaming] exceptions, that's just how it is, especially if both CPUs are overclocked.
If I were the one buying, I would build an Intel Ivy Bridge rig if overclocking is the goal. Haswell is faster at stock, but quickly develops heat problems when overclocked, allowing Ivy Bridge to catch up. If overclocking is secondary, I'd build with Haswell, because the Z87 chipset has more native SATA 6Gb/s and USB3.0 ports than Z77.
Edit: Good point from inzone; I had not even considered Sandy Bridge-E. I'm not sure how much difference in actual use all those extra PCIe lanes make, but I can't see them hurting.