The majors will always have personality testing for one reason: Germanwings Flt 9525. Also some lesser events like the JetBlue PIC although that could have been something that developed well after he was hired. My previous company had a pilot who had a serious personality disorder. In lieu of firing him they let him use up his 3 years of medical leave then terminated him. Afterwards some Security Alerts Came out about him trying to access a flight line at various FBO's.

B737 vs. A320. I flew both back in the day at USAir. At NetJets I rode on both quite a bit when positioning. The A320 cabin width is 12' 2" while the 737's are 11' 7" so you get an extra 7" on the bus. Makes a difference. A320 cockpit was very roomy compared to the 737. A320 did not have the "feel" the 737 did, I'll admit that but overall I liked the A320 a lot more, but then I'm a computer geek so the bus appealed to me.

Keep in mind the A220 isn't really an Airbus product, it's Bombardier where it was known as the C-series. So it's going to be quite different from native Airbus products.