I'm gonna have to go with private on this one. From what I'm hearing around here, some of the top campus PDs around are private (MIT, NU, Harvard, BU, BC). As with anything, it depends on the specific comparison and situation. However, it looks to me as though the best private campuses are better than the best public. I'm thinking in terms of pay, benefits, activity, and administrative support.
It depends on what you are looking for. That can vary from person to person. I have worked in both entities. Granted, I am making about five grand more a year now, I miss the state. I had so much time off that I did not literally know what to do with it all! Can we say "Bunker Hill Day off?!?!" Myyyy goodness.
Private sector pays more, and may or may not be more liberal and may or may not be more squared away. As a general sense... Sate is better due to the:
1. Time off
2. Bumping privillages
3. Lateral transfer privillages
4. Early retirement incentive