Everything you listed after the fire TV is shit.

For the record, MiBox sports a 5.2v 2.1a power supply serviced by a ginormous metal heatsink that covers the top cover.

You have exactly 2 chances for meaningful replies. None of the pretend tv boxes you mention have much of a following in this reddit. Suggest you pursue comprehensive answers in freaktab fora.

Out of that list only the Mi Box is an Android TV device so this being a sub dedicated to that operating system, my obvious recommendation is to get the Mi Box.

The MINIX U9 has the best heatsink and thermal management out of all the supposed "overheating" devices listed. It does NOT have overheating problems, simply due to the massive heatsink MINIX uses.

And with the right software like LibreELEC Kodi Krypton running on it. It will wipe the floor with anything else if you need local content - SDR and 4K HDR with auto everything working. Results are smooth video playback with the correct resolution and color outputs:

https://forum.libreelec.tv/thread/9759-choosing-a-s905-s905x-s905d-s905w-s912-box-guide/