Branagh would work too.
I must admit, I like Boyle's style for the same reasons you've listed! I think it makes him very diverse and unpredictable. And I think if he were to make a Bond movie, he'd probably make it very stylish, maybe Hitchcockian (sort of North by Northwest meets 1960s 007).
I think after Skyfall's success, they will probably look for another British director of comparable clout to Mendes, so after the three just mentioned, the list is probably quite short. Roger Mitchell (who has already worked with Craig IIRC)? David Yates? Matthew Vaughn?