I'm surprised that the general sentiment here is that Teams is terrible. I've been using it for a very long time and have had almost zero issue with it. I prefer it in most cases.

We are currently moving from Teams to Slack at my workplace and I miss the ability to view my full calendar, join meetings, schedule meetings, share common files, and call others all from one application.

Is there another application that does all that Teams does but better?

Typically, people who’ve had a good time with a product don’t write about it as much as people who’ve had a bad time. Anger motivates venting whereas being satisfied with the product doesn’t create emotions that compel people as strongly to share. For this reason, I believe samples of feedback such as this online forum are often poor indicators of the general experience, as is true with many forms of feedback. In fact, I have a generally positive impression of Teams, and I wasn’t planning to write anything until I saw your comment.