I propose adding a trigger that allows you to create rules based on the time of day. As an example, I might make a rule that if it is between 9:00-17:00 then open Chrome. And if it's between 17:00-23:00, then open Firefox. And if it's really late, open Safari to drive me nuts ;-P
Josh M commented
This is my pick for most desired feature, along with the day of week as noted by Dean. Bonus points for providing a default setting of 9-5 M-F.
Drives me crazy when I have a random link somewhere, in an app that isn't listed in my declared personal or work apps, and it opens the personal browser in work time.
Dean Matthews commented
Include the day of the week as well. So that on weekends, regardless of time, it uses my personal browser vs my work browser