windows sever 2019 was based on windows 10 version 1809.
so maybe pick that? consider avoiding the the "lastest" 1903 or forthcoming 1910. the newest versions tend to break things and slowly get patched. keep a backup so you can revert to 7 or 8.1 in case 10 doesn't like your hardware.
then setup the computer to delay feature updates as long as possible. you don't want you main computer randomly updating drivers and rebooting as win 10 is prone to do.