I have been to a dozen or so. The biggest surprise has been Budapest. I expected a grim communist era city but it constantly reminded me of Paris (which is my personal fav). Parks. Wonderful old buildings. The Danube through the middle. Great food.
Some pics - all taken from the Hilton Buda Hill - the morning & river pics were taken through a window.
Morning mist:
Looking north:
Pest at night:
Ian