737 has the best domestic trips by far. Helps a lot that it is still a growing category. Airbus trips will be getting better over time as more 321s come online.

Like others have said, it is an insanely loud cockpit and an ANR headset is mandatory. Slowly more and more captains are getting ANR headsets yet very few like using the intercom. I keep pressing them all on using it as it makes life so much easier.