Not sure what islands you're visiting, but if it's Jamaica, they have some good coffee. It's about $6/lb. to purchase and around $1.50+ for a cup. The other islands I've visited have coffee, but nothing extra special. San Juan makes some really strong coffee, very bitter. The best coffee is in Hawaii-the Kona coffee and it's pretty pricey.
Most of the island's mountains are not much more than 3,000 ft. At that level only Robusto beans grow and in the industry we call it "scrub" coffee because most of the nutrient goes into the plant and not into the fruit. Mountain Grown, truly is the richest kind (as Mrs. Olson used to say(, however between 7,000 and 10,000 feet is where it does best.
Jamaican Blue Mountain is good, but like Kona has a short season.
It is a question much like the "which ship is best" question because it mostly about personal taste. If you are daring or you like to experience new tastes, you may want to try the coffee grown in the Caribbean. Penny made her observation on Puerto Rican coffee, which I think is a pretty accurate point.
One thing to note about buying Blue Mountain coffee in Jamaica...please don't buy the stuff you find in the t-shirt shops and other souvenir stores. This stuff is most likely old and not something worth what they charge. It is a better idea to simply buy it from a reputable coffee shop at home or from a known internet source. Someplace with a good turnover of their inventory.
Me? I am pretty much a 100% Colombian man although I sometimes buy some grown in Africa.
Yes, Kenyan is great. I also like Ethiopian Yrgacheffe. As a foodie, I often find myself buying cookbooks at Jessica's Biscuit. They sell coffee too - sometimes I get a free bag if my book purchase is large enough.