So you have them both but want someone to test them head to head before you open yours?

SO first of all, you are very misinformed about AndroidTV. There is NO emulation, these boxes are NOT emulating AndroidTV. AndroidTV is an OS, same as normal Android. You get the AOSP source and you adapt it for your hardware. Android and AndroidTV are almost the same thing, except Google streamed it off specifically for a 10-foot interface and to be remote friendly, and requires apps to be compatible with it before being available on the AndroidTV Play Store.

Together with that, for certified AndroidTV devices, Google allows them to acquire keys for Chromecast receiver activation. However Google certification and keys DOES NOT imply support for 4k Netflix and Amazon - those services have their own certifications etc unrelated to Google certification.

On to the Google AndroidTV website - I have no idea when this was last updated. My TV brand is not even there, and my TV is most certainly Google certified, plus Netflix and Amazon certified too.

Better to check THIS SITE which is maintained by our local expert /u/513

As you can see, the Jetstream is certified, and so is the latest Mecool KM8 , which is different from the previous Mecool devices that yes had AndroidTV, but no certification from Google. What does that mean in terms of updates? Nothing at all, you are still at the mercy of the manufacturer for OS updates, until these boxes start supporting Android One.

Also please note again, Netflix certification is completely separate from Google certification.

As has been repeated many times, you can only get Google Casting (Chromecasting) on Google Certified Android TV devices. That cannot be faked.

Edit: Excluding the KM8, It's the entire reason nearly all of the Mecool's cannot get any working Casting with any copy protected content.

The Jetstream can Cast copy protected content. It's a legit Google certified Android TV device.

Google are also hopeless updating online lists. I've even seen lists where the Shield should have been include and it was not, and that device has been on the market for 3.5 years.

If you want reliable updates you should be buying Apple, Amazon and NVIDIA Hardware. In that order of priority.

I have the Jetstream and if it is somehow running an unofficial build, Ematic has done a stellar job of hiding it. It runs the Andriod TV Remote app, all the Google Play apps, Google Assistant and integrates with Google Home with no issues.

Don't have any experience with a Mi Box, but I did just recently grab a JetStream and I have been very impressed. I am coming from a Nexus Player which is just very dated at this point (painfully slow). I haven't even used Ethernet on the JetStream and am able to stream 4k content with ease via wifi (I do have a gigabit connection though). For 69 bucks, this little device is fantastic. Definitely recommended.

The JetStream already has some positive reviews. Dual band wifi albeid Fast Eth. Enough ports, working netflix, Dolbi, DTS etc.

The Mi Box S is a cat in a bag. An angry one. Judging from the massive shitstorm that is Mi Box 3 and the fact that it's mostly the same hardware (except for Bluetooth and maybe Wifi chip), i'd say, don't touch it with a 10 foot pole.

I'd also wait for the Amazon 4k (although not necessarily an android TV device) but, the only android tv device actually worth the money now is Nvidia Shield.

In this forum the Nvidia Shield police is going stronger every day. They took the same hardware from 2015 and they said it at 2017 new Shield TV prior they remove some features and they hold the same price! But the police of fanboys protect it as precious jewl, their precious overkill jewl.