Just got a new 4K HDR set and a Shield and was looking for what movies/shows use HDR the best where you can really tell the difference between it and non HDR content. Some of the stuff on Netflix/Amazon on the Shield I couldn't really tell it was in HDR even though they had the HDR label and the TV popped up that it was HDR. Have Kodi too for stuff not available on Netflix or Amazon.
On Netflix, the Marvel shows and Girlboss had great HDR
On Amazon, The Tick and Grand Tour look great
On 4K Blu-ray, X-men Apocalypse, The Shallows, Guardians of the Galaxy 2, John Wick 2
For games, Horizon Zero Dawn, Assassin's Creed Origins, GT Sport
Just watched episode 1 of Planet Earth II yesterday (emby to my Mi Box) - and holy crap. It was incredible.
Just remember the Shield has no auto colorspace conversion/switching in it's Google Nougat Firmware.
When you mix SDR and HDR you have to manually, in Android settings switch colorspaces otherwise you may be sending out the wrong color to the TV:
https://forum.kodi.tv/showthread.php?tid=304226&pid=2694323#pid2694323
On the web, this http://4kmedia.org/samsung-x-redbull-see-the-unexpected-hdr-uhd-4k-demo/
Youtube, The HDR Channel.
https://youtu.be/MuAmv2PsqEw