Boards
Most consistent output by long running bands
I vote for Superchunk. Subtle variations over time, broadened their palette, but still at heart concerned with putting out catchy, lovable power pop/indie rock after 26 years, 10 albums and a bunch of EPs (I know there was a pretty long hiatus in there but if anything it's even more impressive that they came back with Majesty Shredding and I Hate Music after all that time).