I have a hard time with the Google docs is the "collaborative editing and versioning" state of the art bit. My team has several long running docs that we maintain in it, and the UX for finding relevant comments around a blurb of text is bad. You can either (a) never resolve comments so that they always appear in the sidebar, cluttering the doc to no end or (b) tap the comment icon in the top right and scroll through resolved comments that have lost all relationship to the text body. I think there must be better solutions, but vendor lock-in means we'll probably never leave it (at least, not without major disruption).