Client availability is valid. I use an android tv, that’s been easy for me. There are mobile clients for every phone and tablet.

• I don’t know what smart collections are, but I do get automatic collections for franchises (like all “28 x later”) via a plugin. I don’t have playlists, but I guess I never felt the need for one… What would you use them for, binge watching franchises?
• skip intro and credits is a thing, built in since a few versions (used to be a plugin)
• the UI is subjective, and I don’t know any other one… I personally like how it looks, I customized quite a bit, easy to do via CSS.

I’ve never used Plex. What are some of the features that you’re missing in Jellyfin? Genuinely curious.