What I have is a Lenovo T480s, running GNU/Linux.
I don't do anything fancy, some web dev, and some other dev that I do for hobby (nothing like running a game engine heavy).
It's got the following specs:
- 14 inches, 1440P with IPS panel
- Intel iGPU
- GREAT keyboard and no numpad
- webcam in the right position (which I rarely use)
- no OS X (although you /could/ probably run Hackintosh which I wouldn't recommend)
- I would like it to be powerful enough for 5 years
- Great cooling system in my opinion (< 60 deg C under decent load)
If OS X is a must, you should probably get a native MBP.