A few months ago I would of said a new Asus zenbook with ubuntu LTS 16.04 as everything works out the box and 10hr battery life with Linux, however I had to take to service center recently so they could hard reset it because I switched it off and on too quickly (my taxi arrived just as I switched it on, so immediately held button down again) and it never switch on since. Service center being a bunch of idiots wanted to book it in for 2 weeks, I pleaded (with some profanity laced in as they pushed me beyond frustration with their robotics responses) with them to do a hard reset there and then (they needs opening to remove the bios battery), they caved, and surprise surprise 10mins later I have a working laptop again. I probably wouldn't buy Asus again because service centers are truely shit and obviously there is a race condition with the on switch and bios or whatever that isn't fully tested. In fact I bought some torx screwdrivers to do it myself next time.

Dell XPS next I think.