[noggin]

I had a m8s clone (had been rubbish) which had kodi on but this week, so I am now looking for a new box. So recommendations would be great. Main usuage is Kodi and not really much else as my tv does Netflix, Amazon etc.

Things that are a must:
4K
3D
HD Audio Pass through
HDMI 2.0 and CEC
Good Hardware Support
Good Kodi/Openelec Experience

At present I am looking at either Minix NEO U1, Wetek Core/Play, Nvidia Sheild(although a bit expensive) but will consider other options

Wetek Play doesn't do 4K, 3D, HD Audio or HDMI 2.0... It's an older box that is close to end of life.
Wetek Core does 4K at up to 30p via HDMI 1.4, it doesn't do 3D Frame Packed output.
In fact none of the boxes on your list do Full HD 3D Frame Packed output, which is required for full quality 3D. (Only a couple of solutions do)

The new S905 boxes should do most things on your list other than Full HD 3D, though HD Audio pass-through has yet to be seen on them.
The Shield does most things on your list other than Full quality 3D.