Best device/hardware for dedicated media server?

I’m trying to determine what the best hardware option is for me for a dedicated media server. I have a Jellyfin server all set up on my external hard drive, but I don’t want to have to leave my Mac on all the time to use it. I’ve seen some videos where folks say a cheap old PC tower or a Raspberry Pi are options for a machine whose sole purpose would be a low energy cost media server device. Essentially I just want the easiest and cheapest options, something low hassle and that won’t obliterate my electricity bill or device longevity if I leave it on often. Or, alternatively, something so easy to plug and play that turning it on and off it’s a hassle for someone who wants to stream on a nightly basis.

Oh, and if it’s relevant, I’d be streaming to the Jellyfin app on my Amazon Fire TV.

Thanks in advance!

Some recommendations for hardware: https://jellyfin.org/docs/general/administration/hardware-selection

I run Plex on a desk top computer. I recommend getting something relatively powerful because you will probably be adding to your collection regularly and it's easier if you can just rip and or encode new material with the same machine

I have an low power Windows PC with 16 TB of drive space (plus another 16 TB for backups) in the closet. Files are made available via SMB shares.