What OS is everyone running on their Fairphones?

In all of the posts I've seen here on Lemmy, it seems like Fairphones are the most frequently recommended phones; however, whenever people are asking for OS recommendations, GrapheneOS always seems to get the loudest endorsement. Since GrapheneOS doesn't run on Fairphones, I wanted to see what OS's people are actually running on their Fairphones. Is there a clear "best choice" here?