So, I share StageTek's opinion that Building 6 is the best, because I love the frog fountain near it. I also like that side of the resort (the 4/5/6/7 side) more than the 1/2/3 side. Why? Don't know.
Honestly, there is NO worst building. With the caveat that I am a fast walker, the walk from from Building 7 (closest to Riverside) to the food court or the pool takes maybe 3 minutes. If you're in building 2, it would take maybe 2 minutes. It's hard to convey in text how easy it is to get from one place to another. I really would not sweat what building you're in...unless you like the fountains or the trees in one section versus another.