Lots of NYC love here. I've lived in both cities for several years so maybe I can offer a more nuanced perspective. Email's in my profile if you have questions or want some survival tips. And sorry for the length, your question got me thinking!
First, the similarities:
- SF punches well above its weight as far as quality of bars and restaurants so they're about equal here. Both cities have specific things I like.
- Both have gorgeous areas of nature you can visit by public transit. SF has a slight edge here with the Marin County and the Pacific coast, but in NYC you can take the subway to the beach, and it's warm enough to swim. There's even a lifeguard!
- Both have ample employment, especially if you're in tech.
- Both are quite walkable and offer the "table stakes" of city living.
NYC's good:
- Culture & entertainment: Anybody who's anybody performs here. Broadway. Enormous selection of museums, shows, concerts, art galleries, interesting speakers, interest groups, etc. As other commenters have said, this is arguably the best part of NYC.
- Similarly, it's a lot easier to get friends and family to visit you when you live there; nearly everybody wants an excuse to visit.
- Lots of gorgeous parks and outdoor spaces free for the public, well-maintained, and generally safe.
- Significantly better rail transit options.
- Bars and businesses are open way later. Walking home from a bar in SF after midnight is spooky; in NYC, you're often just one of the crowd. Subway & taxis are 24x7.
- You can go to a bar or a meal without hearing a discussion about an app strategy or programming language.
- If you're single, I think it's way easier to meet somebody in NYC, regardless of your preference. It's just a bigger pool, and people have more diverse interests.
NYC's bad:
- Tiny, disheveled apartments. Rent prices. Rent in the wrong building and people can be hostile.
- There's a culture of...honor? Aggression? ...in the city that crosses all races and classes. You can easily find yourself in a fight by accidentally stepping on somebody in the subway (happened to me) or similar clumsiness that would be handled with a polite call-out and apology in SF. One of the biggest unspoken differences IMO.
- People talk about "liking real weather," and summer was nice, but from late October to mid April the sky is flat steel and the wind bites your bones—all the plants are dead and it rarely snows much so it's just brown and gray and grime. It can be seriously depressing.
- Fresh food (fruit, vegetables, sometimes meat) is much poorer in quality in NYC, even at moderately high-end grocery stores. Fruits & veggies can cost triple or more in the winter; they'll be withered and/or moldy in 24 hours. Check the sell-by date on everything you buy, leaving expired products on the shelf is rampant.
- Air pollution is noticeably worse than SF. Can depend on where you live. DO NOT rent by a major road (any of the freeways, some parts of the avenues in Manhattan). SF is small and nearly always has a breeze; NYC has many stagnant days with bad ozone and other lung irritants building up.
- If you ride the subway or take elevators, you'll get sick a lot. It may impact your health long-term, especially combined with the air quality.
- It's noisy and dirty. Ambulances wail like angels announcing the end times. People honk 24x7. Trucks will dump their engine brakes right outside your window. The noise can seriously disturb your sleep; I never got completely used to it, even after years. Whole city smells like piss & garbage when it gets warm.
- I once had a rat run around the corner, being chased by a cat, and run smack into my ankle; both rat & cat sat stunned for a split second then continued down the sidewalk. The thing was so big it actually made me limp for a bit.
- Absolutely gross wealth disparity. I mean it's literally grotesque how gaudy some people and places are.