I wouldn’t overthink it, just get one that is tight fitting, a torso length that doesn’t bunch up when you’re on the bike, and one that you like the look of that you will want to wear.
Unless you are Filippo Ganna, but then you probably don’t need to be asking here
@JohnB I would say that when it comes to separate jersey/bib, as long as the jersey is form-fitting one is pretty much as good as the next.
When riders start to really get serious about textile aerodynamics, they get a speedsuit because if you go from a jersey/bib outfit to a speedsuit you just about always get some positive benefit. After that, if you want to find the most aerodynamic speedsuit for you…then ya gotta actually take some data.