I'd lean more toward Weinberg than Witten, for unifying the electromagnetic and weak forces.
..if you measure who is the greater by which had the greater amount of experimental confirmation, then sure. but if you measure by who proposed the most difficult solutions Witten must certainly be evaluated higher. His output is simply amazing and its across so many topics and fields that it blow your mind. Have you ever read a single line produced by either?
I think superstring theory and quantum gravity will eventually prove to be crap.
Do you understand either?
Like adding epicycles to Ptolemaic astronomy to explain planetary movement.
yah.. its the same. it really is. and wittens field medal in mathematics and his work in supersymmetry and topology is like the Ether theory.