For me, it would have to be (in addition to the given stuff):
1) A new server on Aether so I could still connect with people on Balmung if I wanted (e.g.it wouldn't disrupt a static)
2) Guaranteed housing/apartment (assuming you owned on your server, same size/city at least, both personal/FC) with full no-exceptions FC housing transfer. no shenanigans about not being able to transfer airship or furnishings.
3) Ability to offer free transfers there forever to returners on my friend list (of course it would have to be preserved somehow post-transfer) as well as brand new players I sponsor, regardless of the server becoming closed in the future.

Everything else is ephemeral.