It depends on what you're looking for. I haven't been to Southern, but I think Western is more of a "party" atmosphere whereas Eastern is for relaxation. Both have beautiful beaches, great excursions, gorgeous snorkeling, etc.
I am sure you'll get a more detailed response from others too!
Eastern I like for rest..sea days and Quieter Islands..We are 44 and 53 years old,Western for more to do Snorkeling and sites, and Southern is our favorite for beaches,snorkeling and our time share Island Aruba is in this listing..:grin..it is the warmest cruise and we live in VERMONT and cruise in FEBRUARY to escape winter!!! :grin..we like all the Caribbean cruises but Southern best when it was our Panama Canal sailing..That was PERFECT!!!..and all on Princess cruises..the only one so far in 10 years, not going to mess with the perfect formula that's been our winner!!!...Joanne