My favorite so far has been New Hampshire - lots of space, beautiful forests, cool summers, low taxes, and the general libertarian attitude. I don't really have a least favorite. Even the ones that I felt weren't right for me had their appeal. California was the one I had the strongest negative reaction to. The extent of homelessness in the Bay Area was shocking, but on the other hand the climate was absolutely heavenly. (The two facts are not unrelated.)