My best and worst city is the same: Kathmandu in Nepal. All the beauty and all the worst parts of city life squished and weaved together. This city is a spiritual oasis and gateway to the mountains with a variety of cultures and people, but is a wreck in places. Open sewers and
#1 Dubrovnik (Croatia): accessible to so many stunning surroundings and a great walled city that is almost like a village. Lady Pipi's restaurant at the top end of town is wonderful.
#2 Prague (Czech Republic): historic, great boatels, fantastic for ice in winter and super beers.
#3 Yokohama (Japan): a stunnjing harbour and naval city, with great views of Mount Fuji, delightful museums
#4 Hamburg (Germany): great model railway and submarine museums, stunning parks, scenic and good & chips.
#5 Hong Kong (China): best velodrome ever, easy to travel to tropical islands around it, friendly people, green and where better for East to mix with West (until recently)
WORST:
Changsha, Hunan (China). Many Chinese cities are copied and pasted, rebuilt, over-developed, grey and unwelcoming. This one prides itself on cigarette factories, some branded for MZD. Toilet of a city.