I voted for the 50's.......
But as a bit of a student of history of commercial avation, personally I love the change.
If I wanted to keep mimicing the same A/B/E fleets operating to the same airports, I would have kept playing some other game.
The 50's were a era of HUGE transition in commercial avation. The change from an extremely limited time-sensitive transport system, to the commodity products of today had their beginnings in this era.
Our little world is a bit hyper-devolped, but it certainly can give you the feeling of an airline exec in the period.