Caye Caulker or Ambergris best diving?

[Tjack]

I am headed down to Belize in May, primmarilly to dive Placencia but I have time to kill my first week.

Considering either Ambergris or Caye Caulker, looking for the best diving?

Where can I get the most for the money?

Also looking to do outer atolls, which shops do Turneffe on a regular basis?
Belize Diving Services on Caulker seem to have the best prices but how often do they go out?

Anyone stayed at Ruby's on Ambergris?

Thanks