Question I7 8700 no k or i5 9600k for only gaming in 1080p

If your games are primarily multiplayer, there is a good argument for the 8700 which will have more threads.
But, in general, the higher clock speeds of the 9600K will be better for games.
To get the higher clock speeds you will need a z prefix overclockable motherboard.

If some of your games were among those in this review, then you will see some comparisons which include 9600K and 8700K
https://www.tomshardware.com/reviews/intel-core-i7-9700k-9th-gen-cpu,5876.html