Would be a good place to start, as far as not supporting dell goes. Linux is also a first class citizen w/ system76 - Dell has the factory linux xps13 e.g. but I've heard from a handful of friends who use one at work that its obvious Linux was just kinda slapped onto the laptop at the end of manufacturing or whatever. Support is also probably much better with System76.

For my particular case, the Dell has superior hardware (also, it's about a year newer), but its Ubuntu install has strange problems, and I get crash notification popups somewhat often (including immediately upon logging in for the very first time). The Kudu's install has been rock solid.

System76 has far superior support.