I agree they all sound inviting. Limited to one vote I picked #2 which is the current leader (Scouts First!).
That said I guess it'd depend on the number (and type) of players. My opinions, in no particular order:
#2 is good for a very small group (1-4) and is open to many different types of play
#1 works for a slightly larger group (2-6)* but you do have that nagging mortgage as the main element
#3 is a good standby for a group that doesn't have a ship (I always felt it wasn't required) or when they lose the one they do have or its laid up for repairs
#4 is acutally pretty close to what I have cooking myself
It was kind of mutually decided by myself and my first (and lets hope not last) player for my (soonish) new game. He rolled dice in char. gen. and I found inspiration in reading them.
* or more, I find much more tough to manage, 4 players seems about ideal to me, from both sides of the screens.
I'm sure there are some wheels in wheels and a shadow of a bigger theme cooking in your brain, but if you're not conscious of it yet just let it simmer and see how the game develops