It's less the distros, more the applications themselves that really fail the test. I use ubuntu on a Razer Blade 2016 and it's great but a few apps are horrible scales (due to lack of HiDPI iconography etc.)

Even windows has issues here and there with scaling. Apple really has the best tech here. That said, I switched from a rMBP to the Blade, wasn't excited about the new Macbook Pro's at all. It's a shame too, i've had 10 Macbook Pro's over the past few years, doubt i'm going back now unless the price really drops.

I just got a new hidpi linux laptop. It indeed works good enough on its own, but when I plug monitors in of varying resolutions it is pretty atrocious.

My current work setup is currently 2 1080p monitors, so to work around the weird scaling I just set the laptop display to 1080p when I am docked.

Point being, might as well just buy a laptop with equal or lower resolution to your external monitor(s).