Generally, I expect to like virtually anywhere I travel. Sometimes they end up being disappointing. Here are a few that exceeded expectations.
Germany, Bonn comes to mind. I really like that city. Especially Puetzchens Markt; IMO much more fun (and local) than Oktoberfest. I enjoyed Trier's Roman ruins and the city more than expected.
Scandinavia, I liked Copenhagen better than I expected to. Not so much Tivoli Gardens but there is way more to see and do in Zealand than I expected. Stockholm, I liked the Vasa museum more than I thought I would. The ship is a little newer than my historical interests but I liked everything about the museum.
Spain, I really liked Toledo, but I kind of expected to. The surprise was Zamora, so much history in a small package. Olite castle near Pamplona is now one of my favorite castles in Europe. Holy Thursday in Zaragosa was one of the top experiences of my life. Zaragosa is a town with a few sights that most people could see by getting off a train between Madrid and Barcelona for a couple hours. The Holy Thursday celebration, however, was amazing and virtually no tourists in sight. I also thought Tarifa was a much nicer town than expected.
France, Reims and Chartres were both better than expected. I expected great cathedrals but the towns were a pleasant surprise. The prehistoric areas and port towns in southern Brittany were also nicer than I expected.
England, York was the big surprise. I guess I didn't have any real expectations but came away loving the Shambles area.
Ireland, I expected nothing from Blarney Castle and liked it quite a bit. I think I expected a standard tower house, so the ruin was more enjoyable than I thought it would be. Add the cave, dolman, gardens, woolen mill, manor house and it was much more than I thought it would be.
Italy, the surprise was Orvietto. Much more in a relatively small town than you'd expect and very convenient. I also really liked Siena a lot more than expected.