If you do a google image search for "St Regis Maldives Villa map" you'll see a map of all the villas with hand written numbers on them. Just add "5" to the front of the number to get the full villa number (e.g. "36" becomes "536").

There are OWVs on both the inside curve facing the island and on the north curve facing the ocean. The villas facing the island, can get more sun on the decks and thus have warmer pools during the days depending on where on the curve you are but also have somewhat limited privacy because they face other villas and the island. I would assume 513-516 would be the best if sun and a warm pool are most important to you. The north, ocean-facing villas get less sun but have near total privacy as you can't see their decks from the island or from the other villas. Based on the map, I would 522 and 523 would have the best combo of privacy and lack of JJA villa in view.

Seems like which grouping is better would just depend on personal preference.