I'm not sure Krakow "beats them all" but it is certainly a much better option than Warsaw - I hope my Polish friends wouldn't mind if I describe it, in terms of appearance, as a smaller version of Prague.

Many years since I was in Bucharest but it was grim and inhospitable at that time - I've worked & lived quite widely in Central/Eastern Europe and I wouldn't go again! Budapest is easily the easiest & most relaxed of the cities, Krakow is perhaps a little small and not the easiest to link to your itinerary.

You will need to retain some common sense in Budapest, but the same is surely true of any major city...