Man, almost anything now. Transcoding isn’t really needed very often since streaming sticks (Roku, AppleTV, Fire, etc) now reliably have hardware video decoders. So, almost all the NAS has to do is shove the file over the network. Almost the only way you’d need transcoding is if you wanted to stream video out of your home network to remote devices.
So, if my guess that you won’t need transcoding is correct, then just buy the cheapest NAS that has a couple drive bays.
(There is such a thing as too slow. I have a 2014-vintage Synology DS214se, which was the low end model even then, and Plex clients take up to a minute to load all movie posters, and it can take a minute for a video stream to start. But if you are buying something made in the past few years this won’t really be an issue.)
The Synology DS220j would probably be my pick for that. Or maybe the 120j if you don’t care about data redundancy.
Thank you for the reply. I’m running my desktop as a server and if I could just have everything running off the nas it would be nice. I’m currently using my desktop plus a hd attached via usb as the source so I might as well just clean it up.
Any nas will do for storage (if you can get a + model though for BTRFS) and then for Plex get an Intel NUC or Dell Micro with any Intel chip with UHD graphics 730 with I believe is anything after 10th gen