It's basically Ace's and Ace is part of the Whitebeard Pirates, so the logical conclusion is that it belongs to the Whitebeard Pirates, but if that would be true, then Yubashiri also belongs to the Straw Hat Pirates and all of the other swords that Zoro has, the Straw Hat Luffy wears, Kabuto and so on. But they belong to certain individuals.
In this case, it would be speculation for both cases, we never saw anyone ride it so it is Ace's. It is also powered by Ace's powers, this is what some people would find speculation. In the opposite case, as a ship, just like those minimerries and so on, would belong to the Whitebeard Pirates, just because no one rode it, doesn't mean they realy haven't. Basically SPECULATION. So I go with taking that category out.