A321 from St. Louis down to Florida.
Awful seats. Painful ride.
Hated every minute.
I've flown most modern jumbos in my life but it was just a couple of years ago that I made my one,and only,flight on an A340.
Despite that flight being on a major airline it was almost as bad as my Egypt Air flight on a 707 about 30 years ago.
A319, 320, and 321 are like flying in a phone booth (if anyone remembers what a phone booth is). Not a good ride if you’re going to be more than about 90 minutes in the air.