Haven't been to every US city, but most of the big ones.
Lived in LA for a while - easy to dislike it. I have a special place in my heart for my old hometown, but it's a love/hate thing. Although I still feel I may end up back there some day.
Have to say Indianapolis, Cleveland and Detroit were major letdowns, although thinking back I guess I didn't expect anything from Cleveland and I wasn't disappointed

Baltimore falls in the same category. I was mildly disappointed by Houston too, although it was after Katrina so who knows how many imports helped with the impression (a big part of it was the crime/homeless/druggies, etc).
Just to get an idea of my taste, I love Boston, New York, San Francisco, Vegas and Chicago. Less on the list but still positives were St. Louis, Nashville, and I liked Dallas too.