Each person is entitled to their own view of what is user friendly or not. Personally I find setting up both Tvheadend and MythTV quite complex. For day-to-day use I find both of these quite enjoyable, with a preference for MythTV as it has been better at deciphering and displaying Closed Captions embedded in OTA ATSC shows.
From my experience using Kodi (5 years), Tvheadend (3 years), and MythTV (10 years), all of the front ends occasionally crash. However frontend crashes while watching a recording are extremely rare (at least for me). A restart of the frontend was all that I needed to continue watching. These frontend crashes have not adversely impacted the ability of the backend to record.