From a cpu point of view, there is a massive difference if your use is for gaming.
You go from a cpu with a 3.6 clock rate to one that will hit 5.0 when overclocked.
Few games are going to use more than 2-3 threads so the 6 threads of the 8600K is perfectly fine.
If your main use is for multithreaded apps, then the many threads available on ryzen might be better.