Mostly florida, as the "AMOC" transports the heat away from florida. Could very well be, that a stoppage of the AMOC would create a Hypercane and completely wreck everything in Florida. Cuba could also be absolutely done for. Canada would also probably have a LOT more snow - the Soutpole however would probably stop existing and what exactly is going to happen to Brazil is a complete unknown. Some simulations show the insta death of the rest of the rain forest. Some simulations actually show the opposite. However, Europe, Africa and Asia probably would see a lot lower temps - what exactly that would mean for the Climate in those areas is also highly speculative - however, it's something that happened quite often throughout the history of earth. North America however has lots of other parts liveable, when Florida is "dead" and basically the Sahara.