Depends on what you like. Komodo can be a macro paradise with WA opportunities. It certainly has the best biodiversity in coral and fish. That's my top choice. But the currents can be gnarly and conditions can be iffy (viz etc).
Solomons: it's not crowded and it's relatively healthy. Big fans etc but biodiversity is lacking being an isolated group of islands. Nice mix of wrecks and reef, with decent pelagics. Great viz! Isolated and the flight there is via Oz, the land of draconian airports!
Sipadan: now has limitations on divers going to the island. Still plenty of turtles and schooling fish, but nothing like it use to be. Crowded! Good mix of macro around Mabul/Kapalai and Sipadan bigger fish.
I'd also consider PNG: Milne Bay/New Britain and other areas are very nice. The mix of pelagics/macro is almost as good as Komodo, with slight better conditions.
Palau is also nice, but crowded.