What is the worst airline that you have traveled on?

Delta is the worst one I have been on. We just got back from vacation and both the leaving flight and the return flight had mechanical problems causing 3 hour delays. They didn't have the courtesy to announce what was going on. We just saw a delay message and a gate change flash up on the monitor. They waited so long to post a gate change that we had to Run from Concourse A to Concourse B in Atlanta. If you have been to Atlanta you know that is a pretty long run. I will NEVER fly Delta again even if I have to pay more and have less direct flights.