there are a traditional big 5 orchestras, which I think were NY, Boston, Philly, Chicago, Cleveland. but that list has been compiled a very long time ago. Boston became pretty mediocre over those years, as well as Cleveland. Boston is now probably back up there and rising, because they have the best living conductor (objectively :p) as their musical director. San Francisco is probably as good as any of those on the traditional list, if not better.