If I recall, Oda said that Beckman was the most intelligent character of the whole manga right?
That would mean he's the Shikamaru (Naruto) of this manga.
He said that during the few first arcs ( somewhere in the east blue if i recall correctly) and stated that he is the most intelligent character "so far".
Since then, thousands of characters have been introduced, so i dont know where to put that statement exactly.
My vote is a straight polemic approach:
Main antagonist (BB) and
Main protagonist (Luffy... cmon we all know about sudden shonen main character powerups just because of some resolve... and all three kinds of haki is not something to mess with. Its something extremely rare)
I wonder why everyone ranks dragon so high... i know that hes PROBABLY damn powerful, but in the other battle royal threads, every 2nd member said something like "iam not going to give votes on speculation, since we havent seen him fighting so far". This is the case for me now. Despite that, it has been stated multiple times that bounty doesnt mean power. (But like i said, i do indeed believe that hes the strongest of this group, but aint got no proof so thats it for now)
Same applies to beckman. Having an admiral back up in front of him is indeed a good feat, but we can assume that not everyone has developed as much as the strawheads during the timeskip. Iam inclined to say that only the "weaker" ones improved (rookies and their okamana, marine soldiers with tier <Admiral or Vice admiral) since the whole timeskip would have served no purpose if that isnt the case.
Jozu on the other side is a wild card.. if we apply the laws of phisics, he could probably just turn himself to diamond and wait til everyone is exhausted/dead. But thats certainly not what kubo had in mind while designing him, or else he would be invinsible. So my guess is that armanent haki>diamond (or do you think a regular pirate with a diamond sword could cut vergos body in half? Doubt that, dofla was way to confident in vergos haki , ok bad example, yet haki is the only way to escape a situation where jozu > all, so it kinda "has" to be true that haki-> diamond)