I think it would be less daunting for many if there were 1 or 2 popular alternatives to rally around. Including window managers / desktop environments. (Granted, it's nice they can all coexist peacefully.)
I think Linux is the most popular of the alternatives listed.
There are a handful of popular Linux distros. Ubuntu is probably the most beginner-friendly one with the most staying power; it's the easiest place to start if you have no other ideas/requirements.
The thing is, a healthy ecosystem thrives on diversity. Rallying behind one or two tends towards a monoculture.