Just back form Rangi and Fakarava south.
Both are great spots for drift dive and big pelagics, tons of sharks, mantas, eagle ray and dolphins (Rangiroa only), and if you are lucky also big hammerhead and marlin.
December and january it's a different time though, it's summer in Polynesia and maybe you can see more hammerhead in that period.
For Rangiroa I suggest "The six passengers" (
6 passengers - Rangiroa - Centre de plongée sous marine - Diving center in French Polynesia) a very reliable dive center with 4 dive options per day, very professional and skilled people.
For the accommodation I slept @ Pension Loyna
Rangiroa pension Polynesie Francaise - Loyna a family pension where Loyna - a true polynesian born - serve breakfast and dinner included ........ a clean, friendly place with great food in the evening.
There are more than family pensions there, from mid range hotel like Maitai to a luxury one (i.e. Kia Ora).
Enjoy Polynesia, I really liked this place .... a lot !!