I know Ceara, Costa Rica, and Sri Lanka from personal experience, cannot judge Cabarete though.
Essentially, you cannot go wrong with either of the places, they are all fantastic.
There are some differences to keep in mind, though:
1) Time of the year you want to travel:
* If you like to go in wintertime, bahia salinas is clearly the top pick, wind will be better than Ceara, or Sri Lanka from November till March.
* If you like to kite from May till October, Sri Lanka will have the best wind overall.
* In Ceara, wind picks up typically a bit later (End of July, beginning of August), but it lasts longer (until about January)
2) Sight seeing: Nature
You will see the biggest mammals (Elephants, Leopards, etc) in Sri Lanka. There is a National Park (Willpattu) very close to Kalpityia (essentially the other side of the Putalam lagoon), where it is likely to spot leopards. Many more National Parks half a day away.
Costa Rica has also a very diverse fauna and flora, keep in mind though that the best places are in the South West and East.
North Eastern Brazil is, when you go north from Fortaleza, stunningly beautiful, especially North of Jeri, but the distances are very large, and you will rather see smaller animals, and birds. If you can make it to Lencois Maranhenses (about 2 days by car from Fortaleza), this is a unique place with sweet water in a dune desert.
3) Sight seeing: Culture
You can't beat Sri Lanka on that one. Many beautiful ancient cities within easy reach (about half a day by car from Kalpitiya). Actually, Lonely Planet just voted Sri Lanka the top destination to visit in 2013, it's so interesting.
Culturally, there is not much in Ceara, but the party scene is probably the best of the 3 destinations.
You won't go to Costa Rica for it's culture, either; what can be interesting are the indigenous people mostly living on the panamese boarder in the East (pm me if you need a contact there).
Sri Lanka is the cheapest of these destinations, Ceara should come in second, Costa Rica probably most expensive of the three.
Car rental cost about half the price in Sri Lanka compared to Ceara (depending on the model 4/4 drive car, even less). Did not rent a car in Costa Rica, so cannot compare it.
Lodging should be about the same in Ceara and Sri Lanka, but you probably have more options in Ceara. Food is cheaper in Sri Lanka.
Hope this helps