Been to Bonaire 8 times, week long dive vacations each trip. Visited Aruba one day on a cruise ship stop and did not dive. I've heard nothing about Aruba that would make me pick it over a number of other places for a dive vacation. I have been Curacao curious. But I kept going back to Bonaire. My reasoning:
1.) I already know my way around Bonaire, and the road hugs the west coast. Getting site to site is about as easy as it gets.
2.) While entries can be rough at the start, the swim outs usually aren't real long. Some southern can be a bit.
3.) I'm told the road around Curacao doesn't hug the coast, you have to turn off the main roads to head to some dive sites, and it tends to be a longer trip site to site driving. Roads not always well marked. I do not like asking strangers for directions.
4.) It's been my impression from others' posts that the total number of dives racked up on a Bonaire trip tends to be higher. Doesn't have to go that way, but tends to. Or so I've inferred.
5.) I'm not convinced the facilities at some Curacao sites would appeal to me that much. In Bonaire, I head out in the morning, do 2 dives, go to the resort for lunch and a fast shower, grab more tanks & head out for 2 afternoon dives. I pee in the ocean and dump at the resort, so onsite bathrooms don't matter. I take tanks with me, so nothing to rent. I'm not far from the resort, as the island isn't huge, so I don't need onsite concessions, either. I can see ostriches at the zoo (but if in Curacao, would probably visit the ostrich farm, granted). Diving is about all I go to do.
I may someday be blessed to hit Curacao. It sounds like a fine place.
Richard.