From my times there it seemed that the winds tended to be upstream or downstream (or not much wind). I would think you would want a smallish boat that performs very well with an easy to use spinnaker system. I don't know candidate boats well enough to recommend one, but something with a self-tending jib would be good.
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.