This is tough. I have traveled a lot, as well as living in Germany and Saudi Arabia for several years. I have enjoyed something about every place that I have visited. However, the question is what places exceeded expectations and what did not meet expectations.
I have found that when I first started traveling overseas, I was attracted to places of historical and cultural importance. As I have aged, I have added to that criteria places of natural beauty.
Also, the fondness of a particular place can be influenced by the friendliness of the people, the cuisine and cost of visiting that location.
I love all the cuisine of the Mediterranean. That includes Spain, Portugal, France, Italy, Greece, Turkey, and Middle East.
I find that most people everywhere are friendly, but some cultures not as friendly to strangers.
China was wonderful for the sights and the cuisine, but the pollution in all the Chinese cities is a downer. Also, because of the massive population, cities are very crowded and people are not polite or overly friendly to strangers. Once you get to know Chinese people, they are very friendly. In fact, Germans are a bit like that. Germans are very aggressive in public, but great when you get to know them. We were told that it goes back to after WWII when you had a streetcar for 200 persons, with 500 persons trying to get on the streetcar, there would tend to create aggression. Still, China and Germany were still some of our favorite places.
However, we visited Japan last year and just loved the country and especially the people. Japan is also crowded, but not as much and the infrastructure is excellent. People are polite and very helpful to strangers. The sights are great, but compared to China, still not a match on that account. The country is very clean, tidy and well run, with little crime. The people even dress well, avoiding the grunge that is becoming more apparent in the USA.
Both China and Japan exceeded our expectations.
For Europe, while we love the Mediterranean, Britain has to but high on my list. My ancestors came from Britain and Ireland and I am familiar with the history. The people are wonderful, polite and helpful. Also, the speak my language. The food is better than you would think, since there is so much variety from other countries. Love the fish and chips.
Britain exceeded our expectations.
As a Roman history buff and lover of the Mediterranean, Italy is near the top of my list, especially with Rome. The history in and near Rome is amazing and St. Peter's and the Sistine Chapel is wonderful The Sistine Chapel is to me the most impressive work of art in the World. Rome clearly exceeding my expectations. Of course, Florence and Venice did as well. Spain, Portugal, France and Greece all were great and to some degree exceeded expectations. However, Portugal is special and very much exceeded my expectations. Paris is great, with great sights. I have been there several times and the more that I go there, the less that I want to go back. It is hard to put my finger on why Paris has dropped down a bit, except that after spending time in Normandy and the South of France, those places very much exceeded my enjoyment of Paris. The French people outside of Paris are fantastic and the French countryside is wonderful.
Russia was amazing and the sights exceed our expectations.
The most amazing historical sites still, I found were in Egypt. There is so much that is ancient and well preserved there. Egypt was ancient even when conquered by the Romans. Love the food in Egypt, but it is a very poor country and that does affect traveling there.
Other places that exceed:
Jerusalem,
Istanbul,
Lima, Peru,
Bueno Aires, Argentina,
the country of Chile
The Panama Canal
Alaska
Vancouver, BC
Any place in Australia
The Grand Canyon
Places that didn't quite meet our expectations
India
Indonesia
Las Vegas