I'm surprised that Stockholm hasn't been mentioned yet! Wonderful and well-established food culture, with plenty of old-school cooking as well as experimentation. Due to the local "fika" tradition, there are stupendously good cafes and bakeries everywhere - even higher quality in this department than the better-known Vienna, IMHO. Quite a good variety of different cuisines and fusion cooking as well. Good price-quality ratio in general. Some of the most memorable meals of my life have been had there, and there's always something new popping up on the food scene, which is why I keep going back.
One city which was a great surprise in the food department was Tallinn, Estonia. Small place with touristy medieval-themed restaurants at first glance, but if you dig just a little deeper, it's actually loaded with fantastic restaurants serving up really interesting interpretations of their (superb) local produce and traditional dishes. Outstanding value for money, too (e.g. €7,50 for a dessert at a very high-end restaurant). Hands down my favourite food city out of the three Baltic capitals!
Of course, I do enjoy the big-name food cities such as NYC, Hong Kong and Copenhagen, etc.