Both are super easy to explore independently, I've had no difficulty getting around in either city and English is the only language I speak. It sounds like you will do what you can to avoid tourist crowds, my most recent visit to Prague was in November and the city was super crowded, there were too many tourists trying to see things at the same time. I have heard it's even worse in summer. So, if you want to deal with as few crowds as possible I'd choose Budapest, unless you do intend to see Prague (either now or later). In Prague there is no way to escape the crowds, I would choose Prague if the city is on your must see list. IMO, Prague is the more beautiful of the two cities. November will be cold in both cities, and day light will be short, but the crowds in Prague will certainly be less in November than in summer.