That depends on what you are interested in doing during your vacation. I like Western for adventure, beaches, and snorkeling. I like Eastern for beauty and shopping. I like them both, but for different reasons so we usually alternate each time we cruise..We have yet to take a Southern Caribbean cruise and would love to do so.
If by "Western" you mean Cozemel, Costa Maya Panama, Costa Rica etc then I would say that with the exception of Grand Cayman it's all pretty primitive. And I would definately prefer "Eastern" and "Southern"
We did Eastern (Nassau, St. Thomas, San Juan, Labadee), Western (Labadee, Ocho Rios, Gr. Cayman, Cozumel), Southern (Aruba, Curacao, St. Maarten, St. Thomas). This year we did the Panama Canal and other Western ports (Cozumel, Costa Maya, PC, Costa Rica and Montego Bay (instead of Gr. Cayman--bad weather) . So far it has been our best Carib. Cruise.
Every island you visit has some primitive-ness. We loved every excursion and had a blast the whole cruise. Costa Rica was amazing--seeing sloths hanging in the trees and monkeys frolicking in the trees by the roadside. The canal is fascinating. We had open bar for our 3 1/2 hr snorkel/beach catamaran excursion. WhooHoo! We did an off-road excursion through some (quaint) primitive fishing villages in Costa Maya. In Montego Bay we did a river rafting trip on the Martha Brae. A primitive bamboo raft polled by a Jamaican guide--really cool!
Explorer E. Carib. 1/12/02
Explorer W. Carib. 1/18/03
Summit Alaska cruise/tour
Adventure S. Carib. 2/8/04
Galaxy Panama Canal 2/3/05