The ThinkPad P51 is Lenovo’s top workstation model with 15 inch. You get the strongest mobile Intel Kaby-Lake-CPUs (up to Intel Xeon CPUs) and an Nvidia Quadro up to an M2200 in a military tested case.

The Dell XPS 15 9550 is a great notebook, especially if you are planning to use it on Linux. We've tested Arch Linux on the current model (Intel Skylake i7 6700HQ, 4k UHD display, 512GB NVME) for a couple of days now.