Look for a used Nexus Player, or Nvidia Shield TV
Mi Box is great for streaming apps (Vue, Live Channels, Netflix, Youtube, Kodi, etc)
Shield does that plus gaming.
If just streaming, go for the Mi Box, if you stream PC games go for Shield.
If it's just for Kodi - I haven't had an ounce of trouble with the Firestick. Can't go wrong for £30!
I personally lean towards the SHIELD box for the Ethernet connection. I don't like to stream over WiFi if I can avoid it, too many variables involved that can hurt streaming quality. I love everything about the SHIELD except for the frigging remote.
I know people say connect a USB Ethernet port to the MiBox, but Ethernet over USB isn't all that reliable either. I use it in a pinch as a temporary thing but I wouldn't want to rely on it as a permanent setup. Too bad, they've got a great remote on it.
What's really needed is an in-between choice that has GigE without all the gaming power of the SHIELD. Unfortunately, no one's made one yet.
FYI the MiBox remote won't work with the SHIELD. I tried. :(
If you just need the box for streaming and Kodi I really can't tell the difference between my Shield and Mi. You don't need the Shield power to stream videos. But, if money is no object and you don't have a PS4 or Xbox ), get a Shield, otherwise get a Mi and use you remaining money to buy games.
If recommend the Nvidia Shield or the Xiaomi Mi Box as previously mentioned. I use the MXIII-G2 TV box which has stock Android installed on it. I use it mostly with Kodi, which is set to be the launcher app. This way is a lot cheaper than buying an actual Android TV box.
There are basically 2readily available choices. The Nvidia Shield TV and Xaiomi Mibox. The Shield TV is the best Android TV device and at almost $200.00 it had better be. It's a gaming box wrapped around a TV box. The Mibox ($79.00) however is just a TV box and a pretty good one. It can handle anything the TV viewer needs it to handle on the non 4K side. I don't have 4K so I can't speak to how it handles that.