They all have their individual quirks, advantages, and disadvantages. I think the two biggest factors influencing each of those will be: First, relative seniority in category and the power that affords to bid for a line versus reserve, and a schedule more to your liking. The fastest and most reliable route to relative seniority is being NYC based, and then either the 320 or 737 because the ER may afford more international as you become senior. Second, how you generally handle the expectation-reality gap. As pilots we generally know how to complain about a variety of things, but you may also recognize individuals that aren’t happy no matter how rosy the reality and then there are those that seem quite happy no matter the disaster.