Belizean Shores has a most amazing pool but Xanadu's units, layout and ambiance are hard to beat. It is a much smaller property than the other two.
I haven't been out to Coco Beach since it was being built, so can't say too much about it, except that the pool area looked like it was going to be pretty fabulous. The one unit I was in, was a super large, so probably pretty expensive in the scheme of things.
I can ony speak for myself, but I like to be closer to town for ease of access to restaurants and nightlife. At Xanadu, you will find both tranquility, intimacy and the ease of access.