I got an ASUS PRIME X370-A, and it's been at least okay so far.
I need to send my Ryzen away though, so I haven't gotten too many days worth of testing on it.
Initially it had a bit of a hard time booting with RAM at 3200 MHz (booting itself repeatedly a few times), but after updating the BIOS, it was fine.
The ethernet controller would drop the link down every 1 to 15 minutes or so, and get back up after 3 seconds, but that stopped after the BIOS update as well (not entirely sure if it happened because of said update, however).
A bit of a quality nit: one of the RAM retaining clip thingies feels loose, or more loose at least compared to the others. That is, it feels too light when moved between the open and closed positions.
I also had one freeze/lockup, possibly (hopefully) related to this:
https://bugzilla.kernel.org/show_bug.cgi?id=196683