This is an archive of the MP map review site which is probably the best place for quake 1 multiplayer maps from the old days:

https://mpqarchive.pauked.com/ 

Sometimes it's interesting to trawl around on QW forums to see what they decide to use for FFA servers. Obviously it's going to be biased away from custom maps, of course, but it's one data point.

Like this one https://www.quakeworld.nu/forum/topic/7170/106750/new-redome-small-and-large-ffa was running the following list: (dm1ex, dm2, dm3, dm4, dm5, dm6, ztndm3, aerowalk, bravado, e1m2, ukooldm3

Or this one with a longer, more custom list: https://www.quakeworld.nu/forum/topic/7158/starting-a-new-scandinavian-oldscho 

BTW, this thing I'm about to share here is not SUPER helpful for your question :-) but often when someone mentions Quake DM maps it's fun to link https://docs.google.com/spreadsheets/d/1Py55XH3PZBRCf9kj0yh6ozQsgV7PV0he2PO4GBbssts/edit?usp=sharing

From the guy who ran the Prominence site back in the day.

Lots of browsing-around potential there, at least. I guess come to think of it you can also filter the sheets for things like his "All-Stars" selection (using the filter icon widget in the toolbar), and there's also a separate tab for "Top Picks", so if you want to go off of his review opinion it's there for you. 

Joel, thanks for that sheet, it's awesome! I'll download a few and test them out. The columns allow me to apply some filters to match the stuff we like to play. 

https://www.quaddicted.com/files/maps/multiplayer/

Check also :

https://www.quakeservers.net/quakeworld/servers/pl=1/