One of the best flights I've ever taken was Spirit and had 8 passengers on it, 5 of which were transferring staff/pilots. The second worst flight I've ever had the pleasure of enduring was also Spirit - the worst was Easyjet (simply because their seat dimensions are somehow smaller than the average human and generally incompatible with human physiology), and third worst was Ryanair because a mass of orange colored Brits are with near a unlimited supply of duty free gin is... amusing enough to move it up a few notches.