not much help but i have been to Gizo and Munda but not Uepi and am trying to decide as well. Dont want to go to same place if there is somewhera as good or better.
Munda is amazing
plenty of big stuff and it varies througout the year - i has there May 2010 (19 dives over 8 days) and eagle rays, bronze whalers, grey whalers and silvertips were in residence.
heaps of geat wide angle whip, fan and soft coral to see and photgraph
lost of small stuff, nudis, pygmy seahorse
i did a 8 minure cave dive - no photos - just exciting - you start in a sinkhole in the forest and end up on a wall at 18mtrs (60 feet) - there was a pink fan at the exit with 2 pygmys on it - nice!
several plane wrecks, douglas duntless bomper, zero, hellcat and the best was a corsair sitting upright on white sand in 52mtrs (165ft) of gin clear water. also a 700 tonne freighter (casi maru)
I can not recommend Munda enough - not sure if you are allowed to mention it - but there is a very good dive shop there to take you diving - english couple - watch out they are very hospitable and will keep you company at the bar for just about about as long as you want. (saying that they are a padi dive centre and very professional) - in the Solomons 5 beers after a days diving is regarded as being polite and in no way can be considered excessive. Solomon dive guides were top notch and can find pygmy seahorse as if they are 2 ft tall!
accom at munda (anges lodge) is very good value and you can go budget or pay a bit more for air con and a fridge.
i have some Gizo and Munda photos on my face book page
hope this helps
