Every time we go to Bonaire we see mosquitos everywhere. Have to even use bug spray at night or they get us. Huge ones, too! Every night we would walk around our room and kill them before bed but always woke up with at least 1 bite from during the night. And don't even go out to eat at night without bug spray coating your legs. They get under the tables and eat you alive.
Roatan we always use Cactus Juice for the noseums and never have a problem. One or two bites, gone in a day, nothing bad. Mosquitos we only saw at dusk and used a bit of spray on our legs, no bites.
So from MY experience, Bonaire was much worse for bugs especially mosquitoes!