The band I’ve listened to most over the last six or so years is undisputedly Montreal’s A Silver Mt. Zion Memorial Orchestra and Tra-la-la Band. (or A Silver Mt. Zion, for short). Often called post-rock along the lines of Godspeed You Black Emperor! (an easy comparison as the bands overlap 2-3 members), I tend to think of them more as punk rock with cellos and violins with all members sharing the singing.
Think long 15 minute songs that build and build and overlap with layers of vocals, distorted guitar, and strings. Match that with ‘non-selling out’ principles along Fugazi and Ani Di Franco lines, and anti-establishment politics, and there you go. 2005’s album Horses in the Sky is a good starting point for new listeners.