If you're interested in adding LaTeX to that list, you might like to try Overleaf [1] -- it's an online collaborative LaTeX editor we built to try to lower the learning curve (I'm one of the founders).
It includes a rich text mode for easier collaboration with non-LaTeX users [2], and you can also write in Markdown if you like :) [3].
Feedback always appreciated if you do give it a try, thanks.