I might know a thing or two about these boxes...

• as already mentioned they run Android TV, but it is an unlicensed version so you get no reliable Google Chromecasting because of a lack of Google supplied - Chromecasting keys.
• yes these devices are rooted, and that adds a whole bunch of extra functionality. You may need Magisk Hide to cloak root status from those Apps that check for it. See post below.
• On any device you need a Gigabit Ethernet port for reliable 4K video streaming. USB3 > Gigabit adapters with ASIX or Realtek chipsets work on these devices to add that Ethernet bandwidth.
• there is no copy protected 4K Netflix streaming because these devices have no HDCP 2.2 keys. They have HDCP 1.x only.
• Only the NVIDIA Shield can run Android - Amazon Video properly. Good luck with these boxes.
• the (AMLogic S912) M8S Pro L is faster than a Mi Box and runs Android (TV) v7.1.2
• .

But what really set these devices apart is you can dual boot from a microSDHC card - LibreELEC Kodi Krypton. You will then have the best Kodi Krypton going around that can auto refresh, auto resolution and auto colorspace switching when watching SDR and 4K HDR video content. With HD Audio inc. Atmos and DTS:X. support. Deinterlacing for OTA TV works properly then as well.

The NVIDIA Shield does not even have support in Nougat Firmware for auto colorspace switching , and when it auto refresh switches to 24p in 4K HDR Kodi or SPMC you end up with 8bit color depth outputs when it should be 10bit. Why care about that ?

Well users do not want to see bad color banding in video output from 4K 10bit HDR REMUX's.

Basically the Shield has badly broken incorrect colors and bit depth output when 4K refresh switching. That is the stuff as Lon puts it "home theatre" enthusiasts care about.

Not official ATV boxes despite what the title says. No Chromecast support is a big giveaway.

I have no issues with these boxes, other than the fact that people are being tricked by them. The ROMs being used are pretty stable. If you don't mind losing Chromecast support, these boxes are ok. Just research what you're buying...

So it's an even shittier Mi box, but with 7.1.1

I actually picked up a Mecool M8S Pro W box that was supposedly official Android TV. Be warned: it is not! It's a completely hacked version on a rooted box. Apps that don't run on a rooted box will not run on the M8S Pro W. Verified with a root checker app.

These are more 'hacked' trash like that other box that was recently posted here & pretending to be ATV due to hacks, but is not in the end.

Should be removed from here & reposted in /r/AndroidTVBoxes