I really have only ever used either of them as a DLNA server, but I was recently forced into Jellyfin and find that I like it much better than Plex. It’s faster and more reliable on my system, and for my stripped-down needs, it’s a perfect fit. I’d say that if Jellyfin is doing the job you need, you’ve got absolutely no reason to switch.
I’ve been bitten a few times by dogs and most of those bites were from Chows. I despise and have learned to keep my distance from that breed. The blacker the tongue, the blacker the heart.