All four of the large carriers have network coverage on the islands, and all of the
real MVNOs provide service out there. That said, the two best coverage maps are with Verizon and AT&T. Depending on who your previous carrier is, there's no reason why you can't just stick with them and keep your handset working on an MVNO of that carrier. That alone will save a lot of money and time. A list of recommended and reliable providers is in
the guide.
As for Republic, it's no big loss. There really are better options for the money if you just research a little and run the numbers.