Toggle accounts at upper left
As a user with multiple accounts, I would like to toggle through my accounts by clicking the account icon at upper left sidebar. Right now, that icon gives me an annoying drop-down menu. Much faster to be able to toggle and cycle.
Alternatively, you could move the stack of icons located at the bottom of the left sidebar up to the top, replacing the icon-with-vertical-email-address configuration at the top. There's no real need to have access to the accounts in both places. However, the current layout is very attractive, and it's nice to see the vertical e-mail address. Therefore, I recommend allowing us to tap/toggle the single icon at upper left to cycle through the accounts, and leave the bottom stack of icons in place.