There's vision / creativity and then there's raw compute & storage power and the ability to cross-reference. Einstein seems first rate in category #1 but 2nd rate in #2. VNeumann is maybe a decent candidate for smartest human ever, in terms of category #2.. he was a prodigy staggering adults with math/linguistic feats of strength at a point in development when Einstein was probably still stuttering. But being intuitive has it's own advantages and it takes all kinds of people to build our vast wealth of knowledge.
The thing that fascinates me about Von Neumann is his apparently "normal" personality given his savant nature. Dude liked to do earth shattering work in front of the TV and was quite a friendly, if not a bit socially awkward, person.
