Well, from my point of view, the UBports operating system is the best mobile operating system so far.
Good means, not having millions of apps, good means it's open source, no secrets and the best fact is the convergence.
Convercence is where all operatingsystems like to be. Windows, Android and Apple, they are all aiming to that destination.
Windows failed so far, but I am sure, it will not stop. Android is not a good desktop operating system at all.
What makes Android strong is the brutal marketing of Google. What makes Windows strong is the brutal marketing of Microsoft.
What makes UBports strong is open source, privacy, no spying and perfect convergence.
I am sure it's on a good way for the world dominance
https://github.com/ubports/ubuntu-touch/issues/1
Let's go for rank 1 out of that 307... :-)