100% of my flights from Europe to the SF are A) and 100% of my flights from the SF to Europe are B). Quite frankly the deciding factor here is that the factor that outweighs everything is that transferring at a European airport is speedy, luggage stays checked and I don't need to go through security. Transferring in most of the US from an international to a regional flight is a much more involved undertaking.
The same kind of thinking for me applies to a lot of public transport too. I pick based on how annoying transferring is.