I don't have much experience with others, but I can throw out my complaints about Teams:

* Too much resource usage.

* Chat UX is not good. The team/channel concept makes sense, but threaded (and nonthreaded) chats really just have a bad UI, so everyone at my company just uses multi-person chats, which are terrible for managing access, history, etc.

* For the past while I get some extra prompt about "improving my security" every time I punch in my 2FA info that I have to decline on a daily basis.