We always compare prices and end up booking with Budget at the airport and have never had a problem, some folks have other favorites. There are many threads on the subject on the St Thomas forum on TripAdvisor if you want to research more.

Book in advance, especially in high season.

"Travel changes you. As you move through this life and this world you change things slightly, you leave marks behind, however small. And in return, life — and travel — leaves marks on you.”
-Anthony Bourdain