Oh yeah, I'm with you! I'll admit that Slack's UX and UI is not my favorite either, but at least any challenges are in a single dimension (not like Teams in multiple, challenging dimensions)...Meanwhile Teams' is just awful. I mean, the Teams "rooms" (I guess i call them "rooms" because its annoying to call them "Teams Sites"?) almost exist like channels/rooms in good ol' IRC...but then Teams has channels underneath Teams Sites/rooms...?...Plus, if i want to chat with an indiviodual, those live in the separate "Chat" area...Ugh! To the valid point about slack, at least its all there on the left. I guess i could sort of see if there was drastically different functionality between Chats and Rooms/Sites...but i dont think so. So, why then separate them? As much as i dislike Microsoft as an organization overall (for their historic corporate behavior), they often don't jhave the worse UX ideas...But for Teams, ugh!
I'm gpoing to pivot a little to matrix, and specifically the Element client...which is the most popular matrix web client. I'm an admitted matrix fanboy, so clearly i'm biased...but even Element has areas that are simpler for me to comprehend and utilize...Also, Element in my mind is still waaaaay early in its evolution, and still very much far from their UX being topnotch. But even in Element's infancy is leaps abovew what Teams is now after several years. I acknowledge that Teams "does more" (like embedding Office software, etc.)...and of course the underlying matrix protocol is NOT limited to chat...But, wow, is Teams sucky.