For domestic travel I pretty strictly fly American Airlines out of LaGuardia. I confess that is mostly because I have a lot of miles with them (which I will hopefully use for free trips next summer) and they have great leg room. Also if you only have two carry-ons you can check via their automated check-in machines and go right to your gate, avoiding lines. I rarely have problems and find them to be timely and courteous. For international I fly whichever airline gives the best deal and then it's anything goes. EVERYTHING takes longer and is more of a hassle.
My main beef with traveling these days is the whole process altogether of getting on the damn plane, regardless of the airline. I am so fed up with taking off my shoes at security check points, and one feels like cattle during the boarding process with everyone rudely dropping their wheeler luggage on my head and pushing and shoving.