Which CPU would be better option?

[Mi3lony]

Hello. 
I am thinking about upgrading my CPU.
Currently i have:
i3-8100
asrock z370 pro4
2x4gb 2400mhz ddr4
rtx 2060.
Silentium PC Vero M1 600W.
1920x1080p 75hz 

I know my CPU is not good enough for that GPU that is why i am thinking about upgrade.
I have a dilemma between i5 8400 (240 USD) and i5 8600k (323 USD).
Which option would be better?
1) i5 8400 + 2x4GB 2400mhz ddr4
or
2) i5 8600k (+ later 2x4gb ddr4)?
I am not intrested in OC.
I would love to get stable 75 FPS on medium+ in 2019 or later games.
Which option would be better? Maybe You know even better one?
Let me know  thank You in advance

[191x7]

How about flashing the BIOS (UEFI) to the latest available one and going with an i5 9400/9500/9600K?

[LukeLinusFanFic]

If you're not going to overclock anyhow, the 8400 won't bottleneck you at all, or hardly so. I'd go with that one.

[Lagercat1]

if your not overclocking go with the 8400 or a 9th gen 

[Mister Woof]

I know it's kind of late but, this is why you don't buy low end stuff to begin with unless you have no intention of upgrading.

 

Almost always save money by buying right the first time instead of constantly upgrading.

 

I5-8400 used to be $180 usd, and the i5-8600k used to be $260