There is a lobste.rs thread with basically the same question.
Rehashing and reworking my answer from there a bit:
In general http://www.notebookcheck.net/ is a great site for checking out laptops.
I can recommend the Dell XPS 15, I used it as my work laptop for the past 2 years with Linux Mint 17 and was very happy with it. I now purchased a Dell XPS 13 as my personal couch/travel laptop and am also somewhat happy with it. Build quality for both is superior though.
Minor down point is that the most powerful (especially more RAM) versions for the XPS 15 came with a glare 4k touch display that I have absolutely no use for. Similar for XPS 13 (so mine has “just” 8GB RAM). I also just ordered the new Dell XPS 15 for the new work - the “cheaper” variant has 16 GB memory and a full HD non glare display which is absolutely enough imo and it can be upgraded to 32GB manually if you want to.
The XPS 13 sadly is the first Linux laptop I ever had trouble with which is weird as it is the only officially Linux supported I ever bought. Wifi only worked after package upgrades (good that I had an adapter for wired connection around), plus need to deactivate some stuff in BIOS. Plus the USB-C to VGA/HDMI adapter they sell does not work with Linux… the one I bought only works for HDMI. So, be aware.
As I just got back from researching laptops here are a few others:
- Thinkpads T/X1 are quite nice/good. Also considered an “Ideapad” although I just read they lifted the windows lock on that…
- The upcoming Asus Zenbook 3 also looks very promising, glare display though
- read good things about the HP Elite book.
Personally I prefer laptops without a dedicated graphics card, I have a desktop for that, it saves weight and the switching between internal and dedicated GPU is still sub par in Linux (in Linux Mint switching is
built in but you have to log out/in).
Another note on Linux distributions: Highly personal/debatable topic for most. I’ve been using Linux Mint for… wow almost 7 years now I think. Always have been happy with it, Cinnamon is a nice desktop manager and rather “classic” and good looking. It is based on the Ubuntu Long Term Support releases (17.x on 14.04 and 18.x on 16.04) which I like because then I have the same package base as the servers I run my applications on. It also adds nice pragmatic integration for not totally open source drivers, codecs and others that Ubuntu traditionally mostly doesn’t 
Also if that is a concern for you - the other day I discovered “Play on Linux” as a nice Wine frontend that helps with running Windows games (but Linux game support on steam and indies is growing and great these days).
