My experience has differed from yours. I've recently started using O365 for some client work. I'm really missing a few features from GSuite, that are important for collaboration:
1. Ability to reference a specific person in a comment (e.g. +DamnYuppie please add your thing here).
2. Ability to add/update TOC for a document
3. Comments being owned by whoever wrote them, so others cannot accidentally edit the text of the comment.
4. Ability to notified of and reply to comments by email.
5. Ability to organise documents within my own folder, without creating second copies. (In GSuite, a document is a single thing, even if different people want to organise their own folders differently.)
I also find the UI is hard to get used to. It's different from GSuite, which is to be expected, but it's also different from the desktop version of Word.
Of course I went through a phase of finding that GSuite lacked features that I liked in Excel, but the ease with which you can use Google Docs/Sheets/Slides across devices, and the super-slick display and interaction of the commenting and suggesting features, more than make up for those.