Whenever I fly domestically, I consistently fly JetBlue when they fly that route. Besides for often being the cheapest, especially when they are running one of their frequent sales, they also have great customer service.
Know what you are Entitled to
For example, on Continental, alav hashalom, and still on United, I knew that if the flight was delayed for a while (I think it was 2 or 4 hours, not sure anymore) you are entitled to a $10 voucher and I once got two $10 vouchers for me and a friend when no one else got one simply because I knew to ask.
On JetBlue, it is also important to know what you are entitled to, but they make it easier to you to find out. I have gotten $15 a passenger for a broken DirectTV for part of a flight and I usually hope for short flights that the TV is broken :)
Here is the JetBlue Bill of Rights - a simple, one page guide that lets you know what to ask for
My Wife's Trip Last Night - Free $75 Credit
My wife flew last night on JetBlue and unfortunately her trip was delayed by 3 hours because of a mechanical issue with the plane that had been scheduled to arrive.
I looked up the Bill of Rights and saw that she was entitled to a $75 credit for a 3 hour delay that is based on a controllable irregularity.
I sent an email to customer service explaining the situation and within an hour JetBlue sent out an email saying that everyone on the flight was going to get a $75 credit for their inconvenience.
I am not naive enough to think I got a credit for everyone, but JetBlue did not have to send out the message to everyone, they could have waited for complaints. Even though everyone got the credit this time, it's still important to know what you are entitled to.!