Up until now I've been flying either on Jetblue or Southwest Airlines. My next trip involves a flight to Denver from New York, and since I like to fly nonstop (or at least stay on the same plane), I have two nonstop options: United or Frontier.

Both planes are Airbus A320s with the same base price, so that's made it even harder to decide. Are the differences negligible, or will one airline provide a better experience than the other? Thanks for any suggestions!