After some research I've ended with: [URL] Additional 4k screen via display port, charging, wireless keyboard connected to the dock - all works out of the box.  Some research and practice shown, that security features for thunderbolt ports have to disabled in BIOS to get this setup to work. I've got mine off by default. Looks like Dell TB16 does work without much hassle. 
As in title - what to buy with confidence that it will work without any hiccups? (Stock Ubuntu 16.04)
Dell XPS 9370 Developer Edition - is any of currently available docks is 100% 
compatible with it?