Well, latest gen thinkpad x1 carbon.
Beware that all machines in the world right now are struggling with the fact that windows invented a new sleep method (s3 or some shit, I can't keep track) which ubuntu/the linux kernel / something beyond my understanding doesn't support. LONG story short, some laptops running ubuntu can't sleep when the lid closes.
X1 carbon does now, but for example the HP Spectre does not (which is a shame because it's a great platform).
Good keyboard. Every port you probably need. Fantastic screen. Nub mouse thing. Runs ubuntu great.
If you're worried about transferring from OSX to some flavor of linux that's fair. For me I couldn't get window management like I wanted in OSX so Ubuntu + Gnome is actually a more comfortable environment for me than OSX. I say that as not some old linux fart - I just tried them all and naturally gravitated to the things old linux farts like.
I agree, it is a tough market. I say give a shot to non-aluminum chassis. The Thinkpad may not "look" as tough, but it reeeeally is, I've abused the absolute piss out of mine.