Jellyfin:
- Free
- Gets the job done
- Not in financial trouble
- No layoffs
- Not trying to sell you stuff
- Not selling your watch habbits
- Mainly develops features people want
Plex (paid):
- Decade of development with pretty solid pay features
- Easy sharing with friends and remote watching
- Decent clients for almost every device and more solid transcoding
- Fairly quick fixes for problems
- Great intro/credit/commercial skipping
- Only develops features that might make money
- In the middle of layoffs
- Centralized authentication makes is impossible to watch if offline or they're offline unless you removed local authentication before it went offline.
- They sell your viewing habbits
Plex is super convenient and slimy
Jellyfin is pure and behind on features, clients and comforts.