The Dell XPS 15 is one of the nicest PC laptops available. Thin, light, powerful and available with a 4k display. Linux support is apparently very good, with the caveat that there's an Optimus graphics chipset.
I have one of the latest generation of xps 15- looks and works great. I'm on the final beta of Ubuntu 16.04 using cinnamon 2.8, works perfectly out of the box with nvidias drivers (using nvidia-prime instead of bumblebee to control optimus since bumblebee wasn't cooperating for me this time around)