> Don't you think that it's rather stuff on top of Darwin (e. g. Cocoa and the default apps) and the hardware support that make "things work" on macOS?
You're right. I have never actually used a BSD OS that is no OS X, but I have a suspicion that a lot of the stability in OS X is due to BSD.
> What Linux distributions / desktop environments have you tried so far? Setting up dual-boot on a Macbook is rather good supported IIRC.
A few years ago I spent quite a bit of time playing with Ubuntu. I grew up with Windows, but after 8 came out, I had essentially no desire to ever touch Windows again. People claim Windows 10 is not that bad, but not that bad isn't good enough. Linux Mint was pretty nice as well. Elementary OS seems cool. CrunchBang was nice for a super lightweight system.