I'd get the cheapest and most feature-filled X370 board possible.

When I think cheap and does the job for overclocking, I tend to look at ASRock.

ASRock X370 Killer SLI/ac is 144 bucks on Newegg, probably cheaper elsewhere, but it's X370 and has built-in wireless ac. Can't really go wrong with that (comparable to ASUS Prime X370-Pro, but 20 bucks cheaper, and built-in wifi

For overclocking, you kinda get what you pay for, especially with high core count processors - the more of an overclock you want, the more you want to shell out on the component that feeds the CPU the power. Most of these 150 dollar boards will get you a pretty decent overclock, and most of the top-of-the-top, cream-of-the-crop boards are packed with features the average user won't utilize when overclocking, or, if they do, it'll severely degrade the lifespan of the CPU (for example, the big difference between my Sabertooth X79 and a Rampage IV Extreme was that the Rampage supported ridiculous amounts of current and voltage... And at the end of the day, people with Rampage boards were running overclocks on settings supported by Sabertooth.)

What you definitely don't wanna do is skimp out and get some 95 dollar B350 board without many overclocking features and VRMs that are built around stock clocks. You get what you pay for.

That ASRock is the best compromise IMO - X370, decent support for overclocking, decent RAM speed support, a few extra bells and whistles that are actually useful (wifi is never a bad thing to have on hand, even if you have ethernet cables).