Obviously the 3700x is a better chip but the 2600 will last you a while longer for gaming if you want to wait another CPU gen or two. Realistically outside of benchmark friendly situations (low res, high end gpu) there will be a pretty small difference. If you game at 1440p or 4k then the difference will be close to nothing.
If it were me, I wouldn't upgrade. Upgrading to move up by only one gen seems a bit inefficient to me, but at least you wouldn't have to buy a new mobo.
i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti
Last edited by UltraMega; 08-28-2019 at 12:18 PM.