The 737 is the junior airplane now.
Some people will argue that it's silly is it but when you breakdown why it makes sense.
The Airbus is the better aircraft in quality of job and in general.
The way it's paid also makes it better, people forget the 321 now pays 767/757. Granted it's a bho but that still adds up in the end.
Something else to think about is flying available, the 321s are going to start flying to Europe soon and they already fly to Hawaii.
​​​​​The 737 is the new md-80