After living in the suburbs of California for quite some time, I would have agreed with you. SF seemed like a metropolis in comparison. But after living in NYC for close to a decade, SF now feels like a large suburb with an attached city center. Imo, density/infrastructure/urban-planning-wise, SF feels most similar to Brooklyn, where cars are still very dominant. Brooklyn alone has a density of 35,000/mi^2, where Manhattan alone is at 69,000.

Not knocking on your opinion, just adding my 2 cents. Brooklyn is large, fun, exciting, etc, all the things I’d describe SF as, but I don’t know if I’d call it a metropolis on its own (at least not based on my personal opinion), whereas I would easily describe NYC as so (either defined in its entirety or just Manhattan, which would probably bug the natives).