NHL- Canadiens without a doubt, no one else even close. Easily the most obvious choice of all 4 sports. Anyone saying otherwise just isn't knowledgeable. Look at the titles they won and the teams they beat to win them. Look at the different decades. Its unbelievable even if there were only 6 teams for a while. What they did to Boston since forever is scary.
This is true. I just said Red Wings because they are my favorite Pro franchise, and if we limited the discussion to American franchises then they'd be #1 but there's no denying the history and prestige of the Canadiens.