If you’re only using it for Plex and nothing else, it probably won’t make a lot of difference which you use.
My old setup was Ubuntu running Plex as an install… if you just run a server without a gui, it’s like 3 lines to install Plex
I also have a pi as a portable setup running the docker version which works pretty well but I don’t think it will handle hardware encoding very well, but I could be wrong