That's a hard questions - many choices. I'm not a huge caramel fan, so Norway and France are the best uses for my snack credit. Or a Mickey bar, of course.
I totally agree with the caramel corn in Germany...although my kids also enjoyed the caramel cupcake and the chocolate/caramel covered marshmallows too. Anything with caramel really!!
The smaller caramel corn is a snack credit, but you might need to by the big one when you're done with that one!!
Mexico - We split an order of Nachos at La Cantina, they were very good.
Norway - We LOVED the fresh waffles with strawberries and the Cloudberry Horn
Germany - Anything from the caramel shop
USA - The American Dream - frozen strawberry, vanilla ice cream, and frozen blue raspberry - YUM!
Japan - Kaki Gori
France - Anything from Boulangerie Patisserie - The Strawberry Tart is fabulous
And to drink I loved the Grey Goose Lemon Slushes. We had 4 during the week!
England - We always split a fish and chips basket from Yorkshire County Fish Shop
At the Japan pavilion I wanted to try a unique drink so I asked the CM for advice and she suggested a lychee juice with whole lychee's in the can. It was so crisp and refreshing I can't wait to get it again and try other varieties. I love trying products that aren't available to us at home and the beverage selection in Epcot is excellent.
The ham & cheese croissant from France, which someone already mentioned, is just about enough to be a lunch and can be had for a snack credit! (or was last time I was there anyway.) Great value in my opinion.