By the numbers I'd go for System 76 again, but if the chassis isn't any better these days I'd probably go back to Lenovo.
Admittedly, I use a Thinkpad t430 and a MacBook Air myself, but if I didn't have more laptops than I knew what to do with, I'd be considering Thinkpenguin (though, I'm of the same mind as Linus Torvalds, http://www.cultofmac.com/162823/linux-creator-linus-torvalds... , so I'd be likely to get a refurb'd MacBook Air).
Edit: link to Thinkpenguin site: https://www.thinkpenguin.com/
They are getting very close. I work in very quiet environments and I hate fan noise. Also no moving parts!
I installed some backport which seems to turn off/on at times.
I don't think there are decent brands for linux, or it might require deeper pockets. That's the cost of not working with microsoft.
I'm very happy with the setup.
Something worth to consider :)
Just make sure their chassis/build quality is better than it was a couple years ago. Otherwise in a year you'll have broken bits and a faded scratched screen.