Ask HN: Which laptop for external 4K monitor on Linux?

I'm a software engineer, I have got an outdated system and I was waiting for the new Macbook Pros to be released for a new notebook. I'm quite disappointed by the thing that Apple created (I don't want to delve in that discussion here) and I'm shopping for a new Linux laptop.

I tested Ubuntu 16.04 on a desktop system with a GTX750 card connected to my 4k monitor via DP1.2, works fine.

So I'm shopping for a 4k-external-monitor enabled laptop working on Linux, preferred distro is Ubuntu 16.04. I've seen there's quite a lot of mess about it, since most modern laptops use TB or USB-C docks/adapters that don't seem to work fine on Linux.

Any success story around HN?