I currently have HTPC (plex/kodi) in the lounge and Roku 3 in the bedroom. I run a windows plex server.
After looking about I have ordered a Shield TV for the lounge and a Xaomi Mi Box for the bedroom. Both are Android TV based.
Out of the other options I considered a fire tv but felt I could do more with the Shield TV such as stream games from my pc (need NVidia GPU) and it seems a bit more of beast to handle future needs.
The mi box doesn't have an amazon video app (so I'm told) but I can live without that in the bedroom.
The shield also has an active forum community and it just seems better supported. eg actively getting an amazon app created just for the shield.
although the Roku 3 is good I'm finding mine is struggling with x265/HEVC or heavy Plex content which means more load and the plex server ( and then you start upgrading servers etc). As such its easier just to get a better client device. I've also found it start to struggle with quality 1080p 2.0audio mp4 files which it should be OK with natively.
The other quirk is that the firmware is either US or UK so if you want BBC iplayer app you need to have UK version which then negates the US app options. what finally got to me was that last weekend was Roku not letting me add the amazon video app. at least with android tv or fire tv I can sideload apps.
To be fair the Roku 4 can probably handle more heavier files but I've been put off a bit by the whole thing now.
Theres a good post on GZ about the Mi Box which is worth a read.
Currently Amazon ships the Shield TV direct to NZ for about NZ$310 delivered
The mi box can be found on aliexpress for about NZ$100 delivered - make sure you get the international version (the other one is Chinese only). It might be worth a play with as if you don't like it I'm sure another GZer would take it.