Mark, that is also a question for a good SF area sailmaker that knows the bay. Really depends on what performance you want and what you are willing to do to get it. Also depends on what you want to invest.
Many SFBay sailors have a summer and a winter genoa. Your winds are heavier in the summer and less in the winter on average, and if they don't want to change headsails dependent on the days weather, the summer/winter is a compromise.