These are the apps I'm currently using on my Mi box that are found in the ridiculously skimpy Android TV play store and some that aren't. These few apps should get a beginner up and running for an enjoyable experience straight out of the box. With little to no effort or "fiddling" required by some streaming apps.
If there are better ones please add to the list or make suggestions.
TV stuff....... Pluto TV (ok movies and TV shows), Haystack TV (news feed), Youtube, ABC app(this one seems to be the most polished off the major network apps)
Weather apps.... Weather nation The Weather Network
File transfer and management.... TV file commander
Media players... MX player, Yes player(comes packaged with Terrarium TV),
Side loads.... Terrarium TV (similar to Kodi just WAY less involved), Mobdro(out of the box tv streaming with occasionally a hiccup or two),
Games....gamepad required. Implosion, Alto's adventure, Modern combat 5, Asphalt Xtreme, Assassin's Creed identity(loaded from the play store website)
Music.... Pandora, Google play music
For TV stuff try PuppetMaster.TV with the REKODI repo. Exposes lots of channels to Live Channels and has catchup as well.