Medical school in general is a lot of work and medical school abroad is even more work. There is no centralised application service for electives, you have to look at each one individually. The upper years will have a list of places that they did electives so you'll have a place to start. If you have connections, that would be the time to use them. I chose Atlantic bridge for predominantly personal reasons but, here are some common reasons people pick one over the other.
Pros of Caribbean schools: cheaper, better preparation for USMLE exams, 2 years of clinical experience in the U.S.
Cons of Caribbean schools: really high attrition rates (you either sink or swim), quality of life on the islands can be truly horrific according to some of the people I've talked to who went there, some U.S. states don't recognise degrees from certain Caribbean schools meaning you can't apply for residency there (I also believe you need to jump through a bunch of bureaucratic hoops to even work there when you've finished residency), delayed graduation/zero tolerance (any slip up with assignments or tests and you will be required to either repeat a semester or wait a semester before continuing, this happens all the time and is an immediate red flag on your residency application)
Pros of EU schools: european training, personal/travel experience (many people manage to see multiple new countries while they are there), very low attrition rates (my entire GEP class made it through all 4 years with no one repeating a year although a few had to repeat a course or two) , advantages at certain programs who have a long history of taking EU grads, back up plan (a handful of people do get intern spots although you can't exactly bank on this).
Cons of EU schools: more expensive, more work (you have to take all your Irish exams plus the USMLE exams and/or Canadian exams), less clinical electives in the U.S.