A lot of people hearing 'creature feature' will tend to think 'big animals.' Sounds like you're speaking more broadly.
What's the best destination in the world is relative not only to what you want, but where you are, & how much money & time you've got to invest in the trip. If I were a multi-millionaire and could teleport, I'd probably have hit Wakatobi & Komodo by now! As it is, low to mid-range 7 day trips are on my agenda. I've never been to the Philippines or Indonesia, never hit Komodo or Raja Ampat, places people cite for great species diversity, or Fiji or the Maldives.
So, speaking as a 'local yokel' intermediate regional diver...
1.) Key Largo was one of the fishier destinations I've hit, with a nice array of species, fun shallow reef diving yet the option for some deep well-known wrecks. Conditions vary seasonally, viz. is good but not great, yet U.S. health care is close at hand, and that matters when you've got a baby or toddler with you, as does access to mainland attractions for non-divers.
Trip Report 2013 with Rainbow Reef Divers.
2.) Bonaire is great for high-volume diving. Aside from tarpon, green morays, & the occasional tiger grouper or cubera snapper not a 'big stuff' destination, but you see more creatures when you spend more time in the water! And in Bonaire, if you can shlep that gear around, you can spend a lot of bottom time. I did a solo trip & got in 28 dives (1 guided, 2 boat, 25 solo).
3.) If you like nice conditions, a lot of time underwater, a variety of animals (including a decent number of reef sharks & sting rays, black & Nassau grouper, some other stuff), a live-aboard (for access to better, distant sites, & high-volume diving) out of Belize (for good conditions & a variety of dive site topography) about the Sun Dancer 2 did it for me.
Sun Dancer 2 trip report May 2015.
Here's a thread on picking a Caribbean live-aboard.
4.) Do you like big fish, & you cannot lie? How about the goliath grouper aggregation in the fall off Jupiter, Florida? If you want to get fairly close, see a bunch of them, it's the place?
Trip report with Jupiter Dive Center 2014.
5.) Do you want close-ups with fairly big sharks without resorting to feeding or cage diving? Then maybe you need to see the off shore wrecks out of Morehead City (or Hatteras or Wilmington), North Carolina for deep wreck sand tiger shark diving? On my knees in the 'shark room' of the
Aelous, with sand tigers circling & passing near arm's length from me, good times!
Trip report with Olympus Dive Center, 2015.
6.) I want to dive with sea lions & see kelp! So I'm hoping to hit California next year.
Thread on Southern California Brainstorm'in, where a lot of people helped me learn about the options. Truth Aquatics posted a 5 day limited load southern Channel Islands live-aboard trip for August 2016 on their calendar, and that's looking real good.
7.) I've only got 2 dives in Cozumel & would like to spend a week someday. Great viz., varied reef topography, budget range overall trip cost (unless you want to stay upscale; Cozumel Palace costs more than Hotel Cozumel!), some big stuff, & some people like drift diving. Living Underwater, Aldora & at least one other op. have the option for steel 120 cf tanks!
There are other options you might check into. A few thoughts:
1.) For the ultimate 'sort of diving' creature feature, the great whites of Guadalupe. Cage diving, surface supplied air I hear, but...great whites!!! Expensive.
2.) Tiger shark diving via live-aboard in the Bahamas. Can be cageless. A variety of providers. Fairly expensive.
3.) Oceanic whitetips around Cat Island, Bahamas. I've read enough about how 'inquisitive' these things can be to make me nervous about the idea, but some people love it.
4.) For shark fed divers out of Jupiter, Florida (at least 3 miles out to be precise, due to state law issues on shark feeding), Emerald Dive Charters with Randy Jordan. Pretty inexpensive.
5.) Stuart Cove is famous for shark fed dives out of Nassau.
6.) The Socorros live-aboard trips are famous for mantas, sharks & more. There's a manta night dive out of Hawaii that's famous amongst divers. Not cheap.
7.) Cocos Island & Galapagos are distant and expensive, but they get rave reviews for big stuff. But conditions can be 'challenging.' Expensive.
The options I laid out make sense to a guy living in southwestern KY who likes big stuff. But wouldn't make much sense of a nudibranch fanatic living near the Philippines.
Richard.