Favorite collaboration tool for remote teams?

As a remote-only company (with about 50% of people in Europe, and the other 50% in US) we had great success with a remote-stack consisting of Tandem, Slack, Notion and Google Workspace. Google Workspace, with Gmail for typically external emails, and Google Sheets/Slides/Docs for spreadsheets and presentations, etc. Notion for anything to permanently document internally - like an old style "intranet", as well as planning project features, dealing with incidents, etc. Basically anything that needed to be a bit more permanent over time than being scrolled away in Slack after a few hours. Slack for async conversations. Tandem to effortlessly initiate synchronous communication, as well as to give a sense of presence among your co-workers - seeing who is online and not. Actually - Tandem was a game-changer. Before Tandem people often scheduled meetings just to be able to talk to someone. With Tandem, you just see if someone is online, talking to someone else, busy with something or not. Much more like a physical office where you can look at someone and see "Ah, now is a good time to interrupt".

Slack Topicflow Google Docs

Asana, Slack, and Google Drive