As per the title, im curious as to which may be the best option.
As far as I know, the M8S Pro Plus is Widevine Level 1 certified and has a flashable Android TV ROM so would make for a cheap device. I'm not too fussed about the flashing aspect so this would make for a cheap Android TV box.
Obviously the advantage to the Xiaomi is, it's a little more but it'd be all official.
Price would also be an aspect: £50 - £60 for the Xiaomi or £26 for the M8S Pro Plus.
From my personal experience Chromecast and Voice Search are killer features. Mi Box remote is just awesome and there are not good cheap alternatives to it. So in my opinion Mi Box is worth the price. But still it depends what are you looking for from a box.
I've been considering the same thing - buying an M8S Pro Plus and flashing an ATV rom. I actually already have a MiBox but the lack of refresh rate sync is driving me crazy. Everything is choppy. I'm thinking I might be able to get that working on a rooted M8S. At least in Kodi.
Be aware though, Google cast is not functioning properly on unofficial devices.
If you go the Mecool route, post back here. Would be interested in it for a bedroom tv. Was considering a Mi Box or Fire TV box, but this might do the trick for half the price
Sure mate!
Do what you choose but PLEASE do not expect this forum to deal with issues related to your bastardized Mecool.
No matter what flashing you do, you will not have a fully functional official AndroidTV device and will have many issues that are not seen on original AndroidTV devices.
I've actually tried this ROM. It's stable. Everything mostly works.
Issues:
DPI - The dev. left the DPI at 240, while every official ATV device uses a 320dpi. It's a simple build.prop edit to fix. Otherwise some apps will have weird graphical issues, like the live TV app for example. Things won't line up properly in some apps without the build.prop edit.
Casting - Doesn't work. I have a modified apk that will allow you to cast your screen using the official Google Home app. Send me a msg if interested.
Remote - No voice search. There are a few remotes that you can purchase that have a mic and that will work with this ROM, but it will add to the overall price.
It really comes down to personal preference. Do you like to fiddle with your devices, or do you want them to just work. I like to fiddle, which is why I own official ATV devices and use/make unofficial ATV ROMs for other boxes.