People in low tax burden states like their states much better.

Gallup has an interesting survey asking residents of each state the "Best Possible state to live in" (column 2 on page 2).  Residents of Texas, Alaska, Hawaii and Montana are much more likely to believe that their states are the best places to live, while Connecticut, Illinois, and Rhode Island don't have many of their residents who like the state.  The differences are huge: 28% of Texans say that their state is the best to live in while only 3% of those living in Connecticut, Illinois, and Rhode Island say the same thing.  

The following graphs show that states with low tax burdens and high incomes have the happiest people. 

I also tried average temperature and whether there is a large body of water (ocean, great lake), but those don't add too much explanatory power.  More rainfall in a state seems related to lower levels of happiness.  Even when you run regressions you get similar results.