I've been in 41 so far, though many of those were for very limited lengths of time (1 day or less).
Washington and Oregon are at the top, though both still have their issues. The weather is perfect for me, the people are laid back, the scenery is unbeatable, etc.
The far northeast is next (Connecticut, Massachusetts, Vermont), though I'm less fond of the people there than in the Pacific NW, and cost of living is FAR higher in most cases.
I 'believe' I would really like Maine and Alaska, but so far haven't had time to prove that.
Some of the mountains are next: Colorado, and to a lesser extent Montana and Wyoming (I'd have to be VERY selective about location on those last two).
States I've actually lived in, or stayed in for extended periods, and found to be utter and complete ass: California, Texas, Arizona, New Mexico, Louisiana, Mississippi, Florida, Alabama, South Carolina, Georgia, New Jersey, Maryland, Kansas.
States I didn't like (or don't like on principle), but weren't total and complete ass (just mostly ass): North Carolina, Virginia, Pennsylvania, Nevada (only like at all because of LV/Reno), Idaho, New York (mostly upstate, and the cultural offerings in the city), DC (ONLY because of the museums and history).
Anything else was more or less neutral, or too short to form any opinion.