Being from the New England Area, the obvious answer are the New York sport teams, most noteably the Knicks, Yankees, and Bills. I would include the Jets but they have suffered so much failure as an organization I feel sorry for those fans.
Lakers because they have Kobe and LeBron Stan factions as subgroups to the general LA front runners so it’s a mix of peak annoying spoiled uneducated front runners
I used to think Cowboys fans were terrible when I first moved to DFW. I'd hear the "it's our year!" and they'd be serious. This was circa ~2016.
Most of them are to the point now where they are just sad/satirical when saying it. Packers fans kind of the new Cowboys fans of 2016. Or maybe Lions fans.
A bit of a meta answer but fan bases of teams that constantly winning become unbearable because they are half bandwagon fans that just latched onto a winning team.
so many losers I went to school with became pats fans in college because they kept winning despite having no tie to New England