Have a 2017 Sony TV. Was having similar issues.
To solve the issue for me, In the channels app on the Sony TV i went to Settings > Streaming Quality > Original Quality Delivery > Stream. I get upto 2 slight stutters while the live buffers (first 30 sec of playback?) then is good as gold.
Edit: I got confused who I was replying too, but i think this info might still be useful.
In contrast to your experience, I've gone from the HDHomeRun DVR service (3rd), to Plex (4th, by far the worst), to NextPVR (2nd) to ChannelsDVR (so far, 1st)
With plex, deleting shows is not easy. It makes sense really - its a media server, not a native DVR, but that means going into a menu and going down 6 or 7 options to delete a show. In my time, the Guide data changed twice, breaking all existing recordings. The worst part is that recordings would randomly appear and disappear on the guide. You would genuinely not know if you had recorded something.
The HDHomeRun DVR system had its issues. Guide data would just disappear. I gave up on it after it started to crash regularly on an Android 12 client.
NextPVR was so so close. However, I tried both the Linux and Windows backends. Windows would crash after 5 - 8 days, needing a manual restart of the machine. It would often do this in the middle of the night, meaning morning recordings were lost. The Linux backend had a memory leak for me, that slowed down the client to a crawl (the server rendered the client image for nextPVR). Shame as it only asked for a donation and had some really neat features. Edit: i also remember the deinterlacing was SHOCKING like genuinely terrible on non HD channels.
So far, the only way i've found to "break" channels DVR is to hold down right on the guide. the selection will eventually get lost needing you to press back. I'll finish 2 months then see if the year is worth it.