I have always favoured 2nd class stamp to first. Why? I don’t usually require my post to reach the recipient the next day. I am fairly organised so I always post my letter a few days in advance so that it will arrive at the right time. I only use a first class stamp if I am needing to act upon something urgently.
After moving to England, one of my many observations was that almost everybody here only use First class stamp!
I began to feel self conscious and tried to change my habit. Old habits die hard! I went back to second class stamps after a few months! Years later I am still using second class stamps!