I have lived in NYC and Los Angeles. (also the states of TX, FL, GA, AZ, KY, OH, LA -theres probably more)
I decided finally on SF and have been have been here for almost 20 years.
I wouldn't live anywhere else in the USA. (I do stay in NYC occasionally when work dictates -but poor Gotham has lost its way)
1. Culture - I consider the rest of the USA a giant strip mall/fast food drive-through wasteland. The culture sucks and is isolated, life itself is literally a bunch of bored people who imitate television as culture. It is depressing and wears at my soul/hope for humanity after awhile.
2. People - I like living somewhere I can hear more then a dozen languages daily. Exposing yourself to humanity grows your experience with dealing with others. It's exercise to burn off fatty bigotry and unsubstantiated personal bias. Besides learning creative social problem solving to survive in the City.
3. Money - Face it, the rest of the USA is low population, low density, thus broke. If I am gonna be bored last thing I want is being barely able to afford eating. I can do that at home with the high rent prices on my terms.
4. Beauty - I have one life to live, why not enjoy some of the most beautiful features the planet earth can offer, all packed together. Snowy mountain peaks, to the spread of the bays sheer cliffs and spindly bridges with always perfect year round air conditioning weather.
('nuff said)
5. Food - I love Mission Style Carne Asada Burritos so big they cause a 6.0 Richter scale quake when they thump it down on the counter.
California is the embodiment of the American dream, if you want to make something of yourself -go west son!