I'm mostly only using CCWGTV, both the original 4k model and the budget 1080p one. Neither have performance issues for me (except before filtering out 4k releases on the 1080p model)

I'm just aiming for the simplest/smoothest experience as possible, not so much for myself but so that I can mail it out to my mum who lives out in the bush and just tell her to enter her wifi password and open kodi. She's able to manage from there without having to worry about hdr/dv content compatibility with her display, or default audio language/subtitle display etc.

In kodi you can edit settings.xml for IPTV Simple Client addon to point playlist items to a given category in Seren, make a playlist linking to those categories a favourite, and configure Kodi to open to the favourites menu on launch. That way she has a fully on-rails and custom experience based on her preferences from the point that she runs it.