Assuming that the left gets its shit together before Homo sapiens goes extinct.
My vote goes to either the USA or France. Especially because the Paris Commune already happened. “Smeagol did it once...he can do it again!” Paris seems to have been packed with rioters 24/7 for several years. Not so different maybe from the American Midwest. The ruling class is investing heavily in police in both countries. It’s afraid!
I know this seems partly delusional of me and that there is far more hope in the Global South unifying and then strangling the imperial core from the outside. But still, gun to your head, pick an imperial core country and explain how and why it will fall first. Marx, after all, predicted that socialism would come first to those places that had progressed along capitalist development the most. (Yes, you are invited to explain how wrong I am about this.) The USA falling to socialism would probably cause the rest of the planet to fall the same way.
edit: my choices seem embarrassing now, thank you for enlightening me comrades.
I've been wondering about that a lot recently. Mussolini was able to rise in power by frightening Italy's middle classes into believing that the Bolsheviks were coming for their stuff next. The Nazis enjoyed broad support from the German middle classes. Meanwhile, the socialist nations (or at least the ones who claim they're socialist) that are currently existing all grew out of nations that weren't very industrialized and had small middle classes. I'm starting to be convinced that to the extent that the middle class (laborers who are exploited, yet live in relative material security) is real, it's a detriment to genuine revolution.
I think at the time Marx thought the proletariat had the most revolutionary potential but in the first world where capitalists have stratified the working class further it's only those who are the furtherest exploited that have any real motivation to change things because they lack the security of the labor aristocrats and petty bourgeois. This is also the MLM approach to building revolution in the first world
I mean Mussolini wasn't wrong, we are coming for the private property.