I've always been told that ball pythons prefer long length, shorter heights, and narrow width.
My 40 glass tank is 48" long, 18" wide and 18" tall, and seemed the perfect size. I now have all of them in tubs, in a rack system to conserve electricity for the winter, and they seem happy in there. I suppose they would like to climb sometimes, but I was always told that LENGTH of the enclosure was the most important for balls.
I don't really know the answer to this, as it seems some beeps love to climb, and I personally like to keep them in larger enclosures if I can afford to heat it, and keep it humid!