Re: IC: undecided D&D 5e game
all of them sound great (4, 3, 2, 1, in order of preference).
Specifically:
#4 - sounds like there are tremendous opportunities for intrigue and subterfuge. Built in reasons for the party to work together.
#3 - Party cohesion might be an issue, but I like the 'choose your own direction' of the setting.
#2 - Again, clear, focused, party goal coupled with some good old fashioned adventuring. Love it.
#1 - One of my favorite themes. I've been working on finishing a pirate themed setting I started in 4e. A great deal hinges on how you intend to run ship vs ship combat.