Usually I would say you can't go too wrong with a ThinkPad, but Linux and AMD graphics don't get along well at all. I thought about getting an X140e (or maybe its predecessor, not sure), but picked up a used x201 for dirt cheap instead, because of Linux compatibility. (Incidentally, if the x201 fits the bill at all, I can wholeheartedly recommend it.)
It seems like I hear about great improvements in AMD Linux drivers fairly regularly, but if you look at the actual comparisons, they're still miles behind the competition. If you need actual GPU performance for anything, you should look elsewhere. If you're not both familiar with Linux and prepared to spend some time getting it set up properly, you should look elsewhere. If low-end Intel gfx would do everything you need, and you're OK with the possibility of some stuff not working out of the box, then it might still be an option.
I really like a lot of AMD tech at a conceptual level (APUs, HSA, and Mantle, to name a few), but they seem to have major problems with implementation (not that it's surprising when they're that far in the red). Cross-platform drivers are one of the worse out of a pretty big list of weak points.