We dive in Kona 360 days a year. It is a laid back Hawaii, not busy or over-crowded like Ohau and Maui. We have live music and some places to dance, but nothing like Honolulu.
Most people come to Kona to relax, beach-it, visit the volcano and of course DIVE!
There are many reputable dive operations here depending whether your looking for a cattle boat or a more personal dive experience with one of the smaller 6-pack operators.
I have dove with a lot of them, all have their pros and cons, good days and bad, but I would look to Wanna Dive. They are small but just recently open a retail location right across from Honokohau Harbor- very convenient.
the boat is usually 2-4 divers so you get almost a private experience. The biggest benefit is you can do the kind of diving you want to, and not put up with a "vote"
They will cater the dive to your experience and comfort level.
check them out, the owners name is Steve
Aloha,
brian