Here are some brief (and very informal!) remarks by S. Moszkowski based on a talk "Fermi and Szilard" given by N. Byers and posted on the Los Alamos preprint archives (xxx.lanl.gov, arXiv:physics/0207094, v1 24 July 2002).Byers makes clear the important contributions of both Fermi and Szilard, but also their very different styles. In my opinion, a good society is one in which both the Fermis and the Szilards can do their work. As Byers points out, Szilard saw the danger of Nazism for Europe and the world before others did. Also, he saw his role as doing what he could to get the West to have an atomic bomb before Germany did. While he was very successful in getting some funds for his research, he did not get along too well with the establishment, including that of the Manhattan project. Indeed, at one stage, if Gen. Groves had had his way, Szilard might have been arrested. And he was not allowed to set foot in Los Alamos. When it became clear that there was no longer any danger from Germany, Szilard was the leader in the unsuccessful attempt to persuade the U.S. president not to drop atomic bombs on Japanese cities. So Szilard was socially very active, but his research contributions were not all that extensive.
Fermi saw his role as making contributions to science, and teaching others, and he turned out to be one of the very top physicists of the 20th century, indeed one of the very few to make breakthroughs in both experimental and theoretical physics.(Fermi-Dirac Statistics, Fermi theory of beta decay, Reactions of slow neutrons on various elements, First Nuclear Chain Reaction, Pion-nucleon Interactions) On the other hand, Fermi did not see his role as one of reforming society. So Fermi and Szilard played somewhat complementary roles in the Manhattan project.
It is an interesting mental exercise to ask how these two individuals would have fared in a different society. In fact, we know some of the answers. Take Italy under Mussolini during the 1920's and early 1930's. Political dissent was not allowed. On the other hand antisemitism did not become a serious issue until later when the Hitler-Mussolini axis took hold. Thus Szilard would have been most unwelcome to live in Fascist Italy, and indeed, to the best of my knowledge, he never visited there, even for conferences. At the time, however, Szilard's being a Jew would not have been the issue. Fermi, on the other hand, grew up in Italy. Since he was not politically active, unlike some of the other scientists, he could do his work undisturbed, and the institute where he worked was reasonable well supported financially. This situation deteriorated, however, starting in 1935 when Italy invaded what is now Ethiopa. After 1938, when Italy adopted Nazi type racial laws, it would have become impossible for Fermi to continue, as his wife was Jewish.
Along these lines, one can also speculate in what kind of society a Szilard, but not a Fermi might have been able to function. Probably something like the brief regime in 1919 of Bela Kun in Hungary. Here it was difficult to get any scientific work done due to general unrest, and shortages. On the other hand, a politically active person (with sympathies in favor of the regime) might have been able to manage.