This was a difficult choice, but I’d have to go with the Gorilla Puncher. Why? ‘Cause it’s stationary, and unless it can get some upgrades, it doesn’t stand too much of a chance with stronger foes.
Now as for Arlong’s sea charts, I’ve chosen this but it’s not for as solid as a reason. For one, those charts are of the East Blue, and aren’t necessary when traveling in the rough waters of the New World. I’d say, with the way those charts were accurately drawn, the best one could do is pinpoint the navigator responsible for making them and use them for one’s personal gain. But then they’d have to deal with a certain emperor and, well, would you rather lose against a thousand pirates, or lose against him?
So, yeah. Pretty close calls, but both sides are ultimately a hassle with little-to-no gains.