I use Plex mainly and BBC iPlayer often as well.
My main reason I'd recommend Amazon TVs is I bought a good Android box, it was well specced and got good reviews, but the remote was awful. Amazon TVs remotes are loads better than what I originally used. I'm sure there are non Amazon android boxes come with decent remotes though![]()
Yes, the Mi Box has a great remote, one of the main selling points. And it does all this 4k rubbish.