if price isnt a concern go get the 5960x, it overclocks well and has 8 cores and 16 threads lol. Its hard to pick a top 5 for gaming without a budget and toms hardware has a great way of picking the best cpu per budget as that is the best way of finding the best cpu - http://www.tomshardware.com/reviews/best-cpus,3986.html. For gaming only as I said a i5 is really all you need and the i7 6700k is more than enough and the 5820k, 5930k, and 5960x are more enthusiast cpus, or cpus for cpu intense tasks like rendering, but the 5820k gives quite a bit more performance for less than the 6700k, and with the current cost of the 6700k i find it hard to go with.
Mentioned before the 6600k costs $270, the Xeon E3 1230 V3 costs $275, 5820k costs $380, 6700k costs $420, 5930k costs $580, and 5960x costs $1050.
Now only the 6600k is only a quad core, and the xeon e3, and 6700k are quad cores with 8 threads, and the 5820k is a 6 core with 12 threads and 28 pcie lanes, and the 5930k is the same as the 5820k with a higher out of the box clock speed and 40 pcie lanes, and the 5960x is a 8 core 16 thread with 40 pcie lanes.