I used the following descriptions of benefits/issues in a poll for the group I'm traveling with in December.
The Springs is closest to check-in, the restaurant, and the "feature" (i.e., fancy) pool, so it gets points for convenience. There are three buildings, so it's the smallest of the sections. That may make it more difficult to get into. Also, because of its proximity to the High Rock Spring pool, it doesn't have a separate quiet pool. It's stop 3 or 4 on the bus route. (There were three stops when I was there in May, but people are now saying that there are four.)
Congress Park is the oldest section and is adjacent to the Carriage House/check-in area. The four buildings are a short walk or bus ride from check-in. It's across the lake from Downtown Disney and, thus, can have great views and the shortest walk to DTD. It has a large quiet pool of its own. Congress Park is the second or third bus stop.
The Paddock is the newest currently open section. It's on the opposite side of the resort's pond (lake? inlet?) from the Carriage House area. There are five buildings, making it the largest section in the resort. It has its own quiet pool. If the Carousel section is open in December, however, it will not have a pool and guests staying there will probably use the Paddock pool. The Paddock shares one bus stop with the Carousel and has another stop in the middle of the section. These are the first two stops on the route.
The Carousel section is still under construction, though it's scheduled to open this winter. There are two buildings and no pool. However, if it's open, it will be brand-spankin' new. It's the smaller of the two dashed-line "future construction" sections on this map.
So far, the Springs is winning my poll!