Office has more functionality, without a doubt. File compatibility, privacy/compliance/security, and functionality are key reasons to use it.
Google Docs, on the other hand, the things it does, it does well:
1) Works reliably and without bugs. Last Word document I worked with began crashing Word at some point.
2) Works collaboratively. Google Docs keeps docs in sync in realtime. Office 365 has enough lag to suck at collaboration.
3) Keeps better versioning and version history. Word has a half-dozen different ways to do this, none of which are as good. Again, this is important for collaboration
4) Works better with people outside your organization.
The things it doesn't do, well.... it doesn't.
I've never had issue with Google Docs around UI speed. I have with Word. I think part of the reason is the simpler document structure and format.
In addition, Google Docs has working search tools (so you can find documents), albeit not great organization tools.
For most of my work, I'm not doing fancy formatting or other crap. I'm writing plain text, often on a team. For that, Google Docs would kick Microsoft's butt, if I trusted Google to allow me to comply with legal requirements (Google makes clear I shouldn't), and if I trusted Google not to disconnect my account tomorrow, based on some ML algorithm which decides I look like a scammer, or randomly discontinue something I'm using mid-document.