Sip is excellent as is Bissell Brothers (in the other Portland...Maine). And of course anything from Trillium is a homerun!
I can't remark on Treehouse since it's over 2 hours away from me, you have to wait in line with 150+ people (although I hear they are pretty good at handling that) and they limit it to 4-6 cans per style, with usually 1 or 2 releases a day. Too far and too much time for so little beer.