I prefer Ambanjas, personally. You can still get pretty blues but algo slip in some bars and spots in other colors. There are very high blue 'Banja lines out there, you just have to find the right Breeder.
There are blue ambanjas out there who are bluer than many nosy bes. I prefer ambanjas because I like the look of their rostral process (the nose). Theirs is more prominent than of the nosy be. Hopefully someone will correct me if I'm wrong, but I believe that Nosy bes have very subdued resting colors.