I voted for guild hall as I see it as a more pressing need. There is a need for a place that guilds can meet without party crashers. Trying to conduct guild business with some interloper running around and spamming chat is a pain.
Not that Capt quarters isn't a good idea, just think that guild halls should take priority.
EDIT: After reading Maximus's post I 'll add that I would like this to happen
AFTER new content is added. I kinda assumed that this was a given when discussing these kind of things.