My point is that the question is somewhat like asking what the best python library is. Best...for what? Do you have kids? Do you like outdoor activities like hiking or surfing? Do you like seeing musicals? Are you really into train museums?
As it happens, I live in Chapel Hill NC today, and I'm pretty happy in this area. Not sure that there is anywhere in particular that I would feel strongly compelled to relocate to. But don't relocate here, this place is getting crowded already. :p
That said, I used to travel a lot for work and got to visit quite a bit of the USA, and I can call out a few places that I really liked and could see wanting to live in to one degree or another.
1. Portland, OR, or the PNW in general. I love this area. Not sure I'd want to live in Portland proper, but somewhere in that general area. I like it mainly for the scenery and the outdoor environment. If you like to hike, mountain bike, etc. and enjoy lush green scenery, mountains, waterfalls, etc, places like the Columbia River Gorge are amazing. And Portland does have lots of good food and nightlife, so that's good. The one turnoff would be the frequent rain during a large portion of the year.
2. Chicago. I doubt I'd ever want to live in Chicago year-round, simply due to the harsh winters. But otherwise Chicago is one of my favorite cities in the US. There's plenty to do, plenty of great food, good public transit, friendly people (for a big city), and is just generally somewhere I enjoy being. I've always said that if I ever win big financially in some way, I'd want to have a condo in downtown Chicago to be my second home.
3. New Orleans. Again, not sure I'd want to live here, at least not full-time, but man is it a fun place. And if you like Cajun food... 'nuff said. Also, lots of live music and friendly people.
4. Miami. I have always felt a certain affinity for South Florida, and grew up as a Dolphins fan, so there is some allure to the idea of living in that area. I like the weather there, being near the beach again would be nice, and you can't beat the food and nightlife. And being close to Hard Rock stadium would be big for me. The downsides - sea level rise may bring the beach a little too close, and it may be a bit too noisy, busy, and have a bit too much crime for me to want to be there all the time.