[wrxtasy]

FireTV1/2:
Closed secured Firmware from Amazon, an company openly hostile towards legal Open Source Software like Kodi that threatens their DRM video streaming Business model.
Rubbish deinterlacing, no 24p video sync.
You rely on Firmware fixes from Amazon for Kodi compatibility now and into the future. Like the following problem, that will be likely be at the bottom of Amazon's list of priorities to fix:
http://forum.kodi.tv/showthread.php?tid=246809

And the big one - Koying the Android Kodi developer is not very interested at all anymore in this closed Amazon platform.

ODROID C1+ or the WeTek Core are both about equal in terms of performance when running OpenELEC. The C1+ has the slight edge in speed terms as I've tweaked the hell out of it, with numerous Kodi and Kernel patches and it is now quite fast indeed.
But the Core counters with the extra 2K/4K H264/HEVC resolutions and built in WiFi and S/PDIF. No idea on WiFi range on the Core, the internal antenna looks pretty small on the test box I have.

The RF Remote on the Core is very responsive, but so is the excellent IR receiver on the C1+
There is a nice DAC daughter board for the C1+ called the HiFi Shield that works well with OpenELEC / Volumio / RuneAudio OS if you are an Audio head.

Android - Lollipop / Kodi, its no contest. The Core wins hands down. You will get good Android Firmware support from WeTek and 24p HD Netflix is fantastic.