Literally any of them will crush any game on the market today and the foreseeable future if you overclock them and pair with a good GPU. If you pair these with a GTX 1060 then they'll all probably game about the same due to the middle of the road GPU.
If you're looking for a better long term investment I'd go with a 6850K and X99 if you can afford it and you think the additional PCIe lanes will benefit you. It would be a more logical upgrade to what you have today with a 6-core enthusiast CPU. That said, if you're really just gaming on the machine and not really going to benefit from the additional processing capability of the 6 or 8 core CPUs today or until you think you'll next upgrade, then the 7700K makes sense. Granted, the...