If I recall correctly, it's one of the only states that has a dedicates Court of Chancery [1]- Essentially special courts that are focused on business law, rather than being generalized.
This lets them build up a large body of precedent , but more, it means the judges are going to be dealing exclusively with civil cases, and can can focus on the needs of businesses.
Because of this, the court has come to be regarded as the countries experts business law. [2]
And, on top of that, these startups must pay California taxes and other fees because they're operating in CA (for the SF ones). Not to mention having to do paperwork for two states, and then lose some of the incentives CA gives to local corporations. For example, the minimum $800 franchise tax is waived for the first year for CA corporations, but not for foreign ones operating in CA, ASAIK.
So, with all that, there must be a compelling reason to incorporate in Delaware!!! Anyone knows what that might be?
-Zaid
Legal troubles of any sort are a tremendous waste of expense and time and can cripple any company, big and small. That alone is worth incorporating in a company-friendly state.
Nevada is also popular to incorporate in. I've always incorporated in Nevada because of lack of state income tax and it's favors to small business.