I have to agree that the Aquatic Ape theory seems to make more sense than the savannah theory. You forgot the breathing aspect of the theory, in that we are the only land mammal with breath control and a descended larynx, which are telling indications of a possible aquatic ancestor.
Also, the only other animal with a perpendicular gait is aquatic (the penguin).
We waste a great deal of salt to sweat, which would seem detrimental in the savannah.
No other land animal cries, but the walrus, otter, and various marine birds and reptiles do.
Our glands which secrete oil are huge compared to chimps, and these oil glands are often used for waterproofing.
The list of answers that the aquatic ape theory gives us is long indeed.