I used Plex for my home media for almost a year, then it stopped playing nice for reasons I gave up on diagnosing. While looking at alternatives, I found Jellyfin which is much more responsive, IMO, and the UI is much nicer as well.
It gets relegated to playing Fraggle Rock and Bluey on repeat for my kiddo these days, but I am absolutely in love with the software.
What are some other FOSS gems that are a better experience UX/UI-wise than their proprietary counterparts?
EDIT: Autocorrect turned something into "smaller" instead of what I meant it to be when I wrote this post, and I can't remember what I meant for it to say so it got axed instead.
Inkscape can do a lot, the recent 1.3 update is pretty nice. How well it can replace Illustrator basically only depends on what features you use the most, and if those features are available and/or easily replicated.
It finally has a shape builder tool, for instance. Again, it may not be up to par depending on what your personal workflow looks like, but outright calling it horrid is not appropriate imo.