Should I get Genesis 30 or wait until the mini-dungeon event starts again?

I have a sneaking suspicion that when this event is extended into November, they'll add Pirate skillbooks to the reward list.

I don't have any proof to support that, but it's a good way to get them out there and they'd be worth a fortune. They'd certainly get people doing the event too.

Which pirate skillbook, then, would be the best choice? Picking any random pirate skillbook would be a gamble if you don't know which one to get.
Plus, there would be a lack of demand from the pirate population (which at the moment is nonexistent), so the prices wouldn't be very high either.