and I were discussing this subject the other day in the hangout.
My view is that Slack is very good and Google should be taking a leaf out of their book, and that seems to be happening.
I love hangout chat, but the way they munged it together with hangout video was pretty poor, and it's long been missing some important capabilities like moderation.
With recent changes, I'm hoping they are rearchitecting Hangouts to make it so they can add stuff like this in a better way that they have previously. I have heard, in the past, that the Hangout code base is a bit of a bag of spaghetti.