FDR actually admired Stalin somewhat, not surprisingly, given FDR's own socialist and dictatorial tendencies:

    It is hard to avoid the conclusion that Roosevelt saw the Soviet Union, its record of terror and slaughter, its omnipotent dictatorship and despotism notwithstanding, as containing a greater promise of democracy and freedom than Great Britain. Somehow in Roosevelt's vision all the ugly was squeezed out and what was left was a system in Russia not extremely different from his own American New Deal. Stalin was perhaps uncouth at times, carried the blood of barbarians in his veins, but on the other hand, Roosevelt may have thought, the Soviet Union, with all warts conceded in advance, was still constitutionally pledged to its people to provide jobs, medical care and welfare very much on the order of his own New Deal; more repressive, of course, in fact too repressive, but with a level of repression not of disqualifying importance. There was also the constitutional pledge to build a classless society, which meant the kind of egalitarianism perhaps that Americans had learned from Democratic Party populists. Also the Soviet Union was forward-looking and progressive in thrust, and the aged European imperial states were not.