Would second the XPS13. If you don't want to shell out for a high-end Thinkpad, it is a great option. Mine was the first "developer edition" and it is still running great. There is plenty of support for it on distros aside from Ubuntu. I have run Fedora on mine for years now.

The desktop experience of Linux in general is still a bit off, but if you are like me and spend 99% of your time in the terminal or a web browser it certainly gets the job done. You can always supplement with a VM if you have to run "that program".