It's a slightly strange poll, with so few options for the worst. My actual worst food experince was in Slovakia (which wasn't likely to have featured in anyone's first choice of options, I know): their national dish, halusky, is basically fried pasta with extra bacon fat. It sort of slides down your throat...
I find that it's not so much countries as particular cities that have the best food. And the oustanding city in my own experience is undoubtedly Tokyo, and not for the fancy restaurants (although those are amazing) but the fact that you can find superb little places with a single row of seats at a bar serving beer or sake and a couple of people turning out the most perfect food (from noodles to grilled meats to sushi) in almost any neighbourhood. So it has to be Japan really - Kyoto is almost as good too - they just take food more seriously as part of everyday life.