I grew up only flying American Airlines or Southwest. We fly A.A more often though because the airport they services off of is 2minutes away.(we are 1mile from a runway). That airport services all airlines(U.A,Delta, Qantas, Emirates, Aeromexico etc. etc.) except for Southwest.As for Southwest they service off of an airport 35 minutes away.Our favorite is Southwest due to check bag flying for free,very reliable &safe aircraft (Boeing 737-300) &some other awesome service.Due to convenience we fly A.A&we have never had a problem or delay(knock on wood).The service is just as friendly,they have a variety of aircraft that's safe &reliable too(it's nice to see new airbuses every so often) but they also have the reliable Boeing 737-300 the only complaint I have is just the cost of checked bags.As for my opinions on United Airlines &Delta I can't say much because I never flew with them.I heard Delta and Alaska have excellent service too,as for United I haven't heard much positivity from them.