My favorite alt-history had the Communists winning out over the Fascists in the Weimar Republic. There was a full write up on the alt-history website called "Red Eagle Rises". With Karl Liebknecht and Rosa Luxemborg at the reigns, the German People's Republic is terrifyingly efficient. And, of course, there is no brain drain - all the scientists say, Germany develops the A-bomb and uses it on England. Unfortunately, all of that was lost in a editing FUBAR incident.
Still plenty of other good timelines in the
wiki.