Expand Who and move to sidebar near the top
Leverage the Who Tab to make it easier to find contacts and presence. Add it is a standard button just under Chat and above Teams. Have another Tab, (Just like Collaborators) for Contacts that you can add from your Exchange Contacts, possibly another one for Favourites. Ultimately the ability to create your own Contact Group
The reason I keep going back to SfB rather than operate solely out of Teams is the ease with which I can find people. An expanded Who Tab that I can get to in a single Click rather than multiple steps would be great.