I have stayed at both several times, last time Feb 2013. Big picture, they are very very similar - both resorts are the same size, with a similar resort layout on the same beach (i.e. you will ride a golf cart to get there either way unless you opt to stay beachfront). They differences are more on the design and management/service front. Rosewood has a more minimalist design with good but somewhat aloof but well-trained service. BT has modern Asian design and friendlier and more attentive service in my experience. BT has much bigger villa pools, though no adults only pool, and the lagoon view from the Rosewood villas/pool is nicer. Beaches are basically the same, but I'd give a slight nod to the BT beach (bigger at high tide). BT has better restaurants, but one is Thai so it's helpful to like that - although it's easy to dine anywhere you want at Mayakoba (they run you back and forth in a luxury SUV or boat at no charge). BT also does these ridiculous in-villa BBQ's that are my favorite (not to mention things like private outdoor yoga in your villa). Both have great spas, though the concept at each is different - Rosewood has amazing common areas, while BT has Thai therapists and no common area. Gym better at Rosewood, but both new, nice and not crowded. Fewer kids at BT. And better value. What else...BT crowd mostly NYC/London v. less international and more Dallas at Rosewood. Banyan Tree is the bigger wow for me and the one I keep going back to, but at the end of the day I would say that they're really similar, you can experience both no matter which you decide to stay at, and to go with whichever one seems more your style.