vMax :
The Gigabyte motherboards have been reviewed very well all the way from the Elite upward on the Z390. Everything from the Elite upwards has a 12 phase VRM and they are cost effective. The ASRock Taichi is another good shout as is the MSI Edge at the mid range. The Asus Strix Z390 e has also been reviewd very well though there has been confusion on the ROG series as to whether it is a true 8 phase VRM or 4 phase...the answer is it is a 4 phase VRM but all the same it handle the 9900K.
Top end Gigabyte Auros Master seem to be the best with one of the best cooling and VRM setups and LESS RGB now! A good match for the 9900K though I do find Gigabyte BIOS's lacking a bit compared to ASRock or ASUS...
@vMax, Thanks for the comprehensive reply.....Not a BIOS expert here, so the more straightforward the better. By the same token, overall reliability and functionality, and of course cost is primary focus. Would you mind being a bit more specific as to your recommendations? Perhaps your top 3?
I noticed that some of the MBs are 370 series and some are 390. Is that a factor as well?
And again, thanks for the help.