Which city in California would you rather live in?

My boyfriend has recently been offered two different jobs (with different companies). They both pay around the same amount of money compared to the price of living in each city, and they have very similar benefit packages. They’re both located in California, but one is based in San Luis Obispo and the other is in San Francisco.

I’m from the Bay Area, but have never lived in the city (I’ve also been living in Illinois for about 3 years). My boyfriend is from Washington and has only been to California once. For those of you who know either or both of those areas, which would be a better place to move to, and why?