I usually use what’s available, and has the best file size for the quality. h265 is usually the best in this regard, but I look forward to more av1 encoded content. My Jellyfin server runs on my old school computer, whicj I could buy cheaply from my school, but since it has a sub-1080p screen, it works best as a server with built in UPS for me. It also has quicksync, so I’ve never had to think about which codecs my clients support.