I am not a Sandals fan by any means, but I felt I should weigh in on this question nonetheless. A Sandals vacation will be exactly what you make of it--they don't have luxury accommodations or gourmet food, but most folks who stay at Sandals aren't really looking for either of those things. They want to pay upfront a large amount of money in order to feel relaxed on vacation and not worry about budget. If you and your friends want to go to enjoy a nice beach, a lovely island, and each others' company, chances are you will have a wonderful time at most of the all-inclusives on the island, Sandals included. If you go, intent on having a good time, you'll find a way to have a good time. If you go, intent on nit-picking every little detail and fault, you'll probably not have a good time. There will be mosquitos. There will be noise from roosters, goats, etc. There will be beach vendors. None of those factors will change much no matter where on Antigua or elsewhere in the Caribbean you choose to stay.
As for the other posters, "the best beach" is such a subjective issue that there's no way to prove right or wrong--it's just an opinion. I find Dickenson Bay to be a lovely beach that is good for people watching, but is otherwise too busy for my personal preferences. Others may find it the best beach on the island, or even the Caribbean.