I've been running both Plex and Jellyfin for years and I've had more problems with Plex than I've had with Jellyfin. It's also easier to figure out what the issue is since it's open source, I actually fixed a bug and added documentation for the "Native streaming" in JellyfinForKodi since I was able to dig deep into it.

I've always found that Hardware (GPU) Encoding to be a pain to use, regardless of the platform. It also lessens the quality of the video compared to Software Encoding. Get yourself a stronger CPU and don't mess with HE. I have a AMD Threadripper 2970WX in my home server and it laughs at transcoding 4K with uncompressed audio and Dolby Vision/Atmos. I can do 4 4K simultaneous transcodes with room to spare.

People pay Plex for the ease of remote access. If you can read or watch a video, it's really not that difficult to setup remote access for Jellyfin (they have the process fully documented). There's a key thing here: if you setup the remote connection it removes any liability from the software creators (Jellyfin in this case). If you want to give them $120 or more because you can't be bothered to figure out how to setup remote access yourself, so be it, but you're also at the whim of the company.