Thinkpads work out of the box for every regular feature (I had to write a shell script to make my X1 Yoga handle folding it into tablet mode -- ~15 LOC).

A thinkpad + ubuntu I think, will hit all your needs. Lenovo preinstalls Ubuntu on some of their thinkpads in some cases (afaict, large enterprises). The thinkpad line IIRC works to use well-supported hardware for Linux. You can check the certification list to be sure: https://certification.ubuntu.com/certification/make/Lenovo/

Dell also ships XPS models that ship with Linux. http://www.dell.com/en-us/shop/productdetails/xps-13-linux

I was on the mac a long time, but eventually switched to Linux and am much happier.

EDIT: Thinkpad P series has 16/32gb of RAM, donno about battery/size/weight, as there are a few models, and you'll have to figure out what your preferences are in trade-offs.