Great ! and your favorite of them all is ?
Allround best, easiest to use for Kodi, Netflix, Amazon, casting, IPTV, Sports TV .... playback, most intuitive, by far Nvidia Shield TV. Nothing comes close. It has Android TV. If I want Android on a media player for the TV, I want Android TV. Not normal Android, made for phones or tablets. Shield is very fast and snappy. Allows game streaming if you like.
If I use Kodi, I don't want to mess with external players like you have to with Zidoo, Himedia & Co.
Nvidia Shield TV just works. With latest firmware it supports color space switching. Very nice. For people who like Plex (I don't), it is brilliant.
Problems: No stereoscopic 3D, no iso playback, no 4K/HDR playback on HD/SDR displays.
For stereoscopic 3D, iso playback:
The fake Oppo. (Or real Oppo with jailbreak). Nothing comes close. 3D is perfect, Z-position of subtitles is correct (wrong on egreat, Zidoo and Dune-HD). Supports Dolby Vision.
Problems: Doesn't remember playback position with isos. Fake Oppo Network standby is broken, making IP control difficult. Unless you don't turn it off. File playback is a joke. But you use Nvidia Shield for this.
Networking is problematic. Only SMB1 supported. Accessing Windows 10 shares can be problematic. Never got NFS working. Network browsing sucks. If it doesn't find a share with searching, you are lost. You can't specify a network address manually. Pathetic.
If you only want one device which does everything (but nothing really well):
Dune HD. Hardware identical to Zidoo. Android device in "disguise", uses the Dune HD UI known from previous Linux boxes. Doesn't "want" to be an Android box. Wants to be a "Dune HD" and succeeds. Iso playback slightly better than Zidoo (with complex BD menus)
Or a Zidoo. I like the Dune more, but the difference is small.
Egreat is not so great. Himedia is even worse.
If you only want Kodi and don't care for anything else (no 3D, iso, Netflix, ...):
OSMC Vero or a cheap chinese Amlogic box with LibreELEC.