I'd be happy with GNOME in the 3.x incarnation, but the whole "turn your 7-hour Macbook Air into a 4-hour Linux machine" is just not okay. I need parity in battery life.
Why isn't there a top-tier platform company (or nimble upstart) out there taking the lead and making a machine that has 100% driver support under Linux?
I am holding out hope that the Piston might get us there, but I'm not holding my breath.
How about a Chromebook? They run Linux, and pointedly don't run Windows, so you know the hardware will work under Linux.
I haven't used it or other laptops enough to say how good it really is (but hibernate etc. works, the screen and keyboard are nice compared to other ultrabooks I tried; it's light and clean). The trackpad is annoying though but I think I'll always prefer a mouse.
Battery life is good, the price is great, and the support has always been amazing.
Providing you stick to Intel (eg no Nvidia graphics) then the Thinkpad T series (and probably most others) work very well under Linux. Occasionally there are issues but Lenovo do fix them (eg BIOS updates). Of course Lenovo won't sell you one without Windows!
The only thing that hasn't been supported in my last two Thinkpads (T430s and T61) has been the fingerprint reader. More accurately it is supported in dumb mode, but not in smart mode as it is under Windows. That is largely the fault of the company that makes the reader, although they have been bought by Apple so who knows what happens next.