I've had good luck with TVs from Sony, which would probably be considered higher end based on price bracket. They ship with near-stock Android TV, don't make a fuss about not being connected to the internet, and allow firmware updates via thumb drive. Have had a couple now that I use with an Apple TV, which is a pairing that works very well.
I wonder if Sony are releasing the Linux source code they run Android on and I wonder if their firmware updates are signed. If they do release source and updates are signed, you could probably install a regular Linux distro with Kodi.
Likewise, but the problem now with the built-in software is that Android TV is getting increasingly user-hostile as well. The major UI update they made which added an uneditable promotional section to the top of the home screen eg.
