OH, tough question! One thing to consider is that Mala is accessibly by land whereas the others are not. So if you are in a position to do some shore diving, you could rent gear and go yourself since it's an easy site to navigate. If you do Molokini, I would recommend going with a dive outfit that does the drift dive - starting from inside of the crater then going around reef's end to the back wall. Some outfits will do 2 tanks, one inside and one outside - also a fun way to do it because they are drastically different sites (horizontal vs. vertical reef). Cathedrals and other Lanai dive sites are really fun and structural, lots of swim-throughs and congregations of fish that are harder to find on Maui. LOTS of OPTIONS! Can't wait to find out which one you pick :)

looks to be a grey reef shark to me