There's been some chatter about Celtics vs. Warriors fanbases. There are perfectly objective (or mostly objective) systems for judging fans.
If I were neutral about the teams (I'm not), I'd assess biases away from sports: Political Persuasions and Coolness of City (how's the music/art/architecture?). This is how I arrived at a Northern > Southern rooting system. If I don't have any favorites playing, I nearly always root for Union over Confederacy. Boston vs. SF fanbases are a tougher demographic question. (Mostly) Union, both.
If we examine the cities and regions, Boston mayor, Michelle Wu, is considerably more progressive than SF's. Meanwhile, Mass's senators Ed Markkey and Elizabeth Warren are the Senate's two most progressive titans. The third is in Vermont, also Celtics territory. Heck, even knucklehead Green Ralph Nader is a New Englander. Feinstein is SF's gift to the Senate. In terms of electing progressives both locally and nationally, Boston fans are a clear winner.
Culture is tougher. MA has a lot of bands I love (Modern Lovers, Dinosaur Jr., Pixies, and America's best hardcore scene), but SF has more historic rock bands. The written word, visual arts, theater, classical music, etc. go to Boston. But the Hippies and Beats landed here and, despite Boston being the most collegiate city in the world, Silicon Valley has more influence and sway than university students these days. Culture: Tie.
If Politeness is an issue. Warriors fans win. Easy. Boston sports fans are the second most fanatical in the US. Along with Philly and NYC, they are some of the most knowledgeable... but like most Northeastern and Midwest fans, they are also crude and drunk... actually, probably the drunkest. Philly & NYC still win on crude. Barely.
"Fuck You Draymond Green" chants don't bother me. Boston fans do that to everyone who is villainous but good. And he is villainous. Celts fans have a running catalog of his uncalled fouls. Here's a random foul shot. You gotta stick by him as a Warriors fan. I get it. He's Danny Ainge. He's Patrick Beverley. The warriors might be better with him on the bench, but I still like Green. Every team needs a violent whiner. He will be a great analyst. Or GM. Or whatever he wants to be.
Next, Knowledge & Enthusiasm. My dad had over two dozen books about the Celtics (Russell wrote 5, Hondo 2, Cousy 2). Some belonged to his dad. I used to discuss with my grandparents how Havlicek and Cousy fit into the pantheon of Celtics greats (3 & 4, probably). I don't remember seeing 'em play, but I still watch Youtube clips and think about my dad and grandparents. Meanwhile, the San Francisco Chronicle doesn't even bother to print all the stats anymore. And if the game started after 5pm, it's not even reported. The Bay Area's talented writers are long gone. In their place are cliches and ham. Having spent plenty of time reading both the Chronicle and Globe (Recommended: Hall of Fame Globe reporter Jackie MacMullan's podcast, "the Icons Club"), sports are simply bigger back East. The teams have existed longer (Red Sox are 100 years older than the SF Giants, for instance) and there's a lot less to do in the winter in Boston. So the fans read Celtics books and stew over obscure stats. Fan obsessiveness attracts more talent. I suppose the loop is a bit of an Ouroboros scenario, but it certainly keeps people informed and attuned. Boston wins mightly on Knowledge.
Enthusiasm is closer. Bill Simmons avoids watching games with his family 'cause he's embarrassed by his emotions. I know what he's talking about (for the record, a sporting event hasn't made me cry since 2003. I'm mature now.). Remember when Warriors Fans thought the sky was falling when Monta Ellis was traded? I do. Man, it filled the Sporting Green. But the venom towards ownership and general management was nothing compared to Boston. I was discussing this with Chad. It's funny that Ellis was thought to be the One. But I don't fault the Warriors Fans who cared. It showed some vigor. And that Believe thing was cool. Celts fans take everything too seriously, but I think Warriors fans could catch 'em (they just need Kerr, Green, Iggy to write more books). Tie.
I'd say the teams' fans are pretty even, like the teams themselves.
What cost California sporting establishments the most is that they just don't go back far enough to have grandfathers and grandmothers telling of past exploits. There just isn't the same amount of past. And our weather means there's just more to do in the Fall and Winter. Diversions from fretting over lineups and whatnot. East Coast sports-style fanaticism does seem to have a grip here in football. I've always been impressed by the knowledge and intensity of Oakland/LA Raiders and SF 49er fans.
California Teams Fan Ranking:
[Raiders Knowledge: 9/10 Enthusiasm: 10/10 - These fans know Pluckett's stats. And they really, really love the logo. Of course, the Raiders don't count as a California team anymore. I still can't believe that.]
Niners Knowledge: 8 Enthusiasm: 10 - I remember being in a barber shop debate over Montana v. Young. Feisty and knowledgeable.
Sharks + Kings Knowledge: 9 Enthusiasm: 9 - Have you ever talked to a hockey fan? Fucking weirdos. I never thought that sport would take hold here. Wrong.
Lakers Knowledge: 9 Enthusiasm: 7 - No West Coast team idolizes its players more than the Lakers. There's a Kobe mural on every block. Why shouldn't they? That 80s team is the most beautiful thing to happen to basketball. I hated it. Aside from the celebrity fans, they tend to know their shit.
Giants Knowledge: 8 Enthusiasm: 8. - I have friends who know so much about Will Clark it's weird. But the crowd lately seems more into fashion. Still, pretty solid.
Dodgers Knowledge: 9 Enthusiasm: 6 - It's fair weather as all heck, but I have Dodger friends who really know their Kofax and Fernando stats.
A's Knowledge: 10 Enthusiasm: 4 - Can you blame 'em for an enthusiasm gap? That ownership is evil. Holy shit, though, A's fans know their history.
Warriors Knowledge: 6 Enthusiasm: 9 - Warriors fan knowledge seems to mostly cover the 21st Century,* but they do care. *Disclaimer: Most of the fans I talk to are younger than me and often first-generation fans. Still, they should fucking know who Nate Thurmond is.
Sparks & Monarchs Knowledge ? Enthusiasm: ? I've never talked WNBA with fans of either team. I'm going to assume they're good. I'm really, really hoping Oakland lands a team. WNBA is rad.
Angels Knowledge: 7 Enthusiasm: 5- When I was living down there and going to a lot of Angles games, the fans seemed pretty savvy. Kinda tepid. Needed a monkey to know when to cheer.
Padres Knowledge: N/A Enthusiasm: 7 - I don't know any Padres fans, so I've never really talked baseball with anyone.
Kings Knowledge: 6 Enthusiasm: N/A - I feel terrible for this team. Any one of us could run it better.
Rams Knowledge: Pending Enthusiasm: Pending - I went to a lot of Rams games (friend's parents had season tickets). Back then, there was a dude we sat near who shouted "Sell the team you evil bitch!" right after the national anthem. She moved 'em to St. Louis instead. I wonder if he's come back.
Clippers Knowledge: Disqualified. Enthusiasm: Disqualified - Moving from San Diego to LA is a disqualifying act.
Chargers Knowledge: Disqualified. Enthusiasm: Disqualified - Ditto
I'm not really sure where to place the Earthquakes. Great stadium, fun place to see a match, but every football fan I know cares more about a team overseas and considers MLS to be second-rate. Maybe that'll change. I've been to a SF City FC match at Kezar and I've heard Oakland Roots are fun. But I don't know enough about soccer to even evaluate knowledge.
For comparison, the top in the nation:
St. Louis Cardinals - Knowledge: 10+ Enthusiasm: 10+ Remember when Emmylou Harris checked the Cards score between songs at Hardly Strictly Bluegrass? I've spent some time with Cards fans. Fucking exhausting.
Yankees & Red Sox - Knowledge: 10 Enthusiasm: 10
Knicks & Sixers & Pistons & Celts - Knowledge: 8 Enthusiasm: 8 (deductions for bitterness)
Pittsburgh Steelers & Chicago (all teams) - Knowledge: 9 Enthusiasm: 9 (deductions for obsessiveness)
It doesn't exactly fit (they're comparing hardcore styles, not Celts/Lakers), but still fun: