I find the usability of the file picker for Google Docs to be below par. The only way to quickly attach a document that I currently am working on in another tab is copy & paste the title of it into search, wait a sec, and then click the autocomplete result. The list of folders that it presents by default is pretty random and therefore not useful.
We also use Slack. Their Google Docs file picker is much more usable. 1) it doesn’t seem to make me click on the my google account as much for authorization, 2) it shows recent docs at the top of the initial list – that is great! 99% of the time the doc I want is there. Often, attaching a doc with their system is 3 clicks.
Same action in Asana takes more clicks, copy & paste, and tab-switching. 