Here's one of the best Hunter build in Phantasy Star Online 2. The build focuses mainly on damage and that being said, you'll see here a DPS build for Ranger in PSO2.
Before we go to the nitty-gritty part of this page, let's see the build first.
With the essentials covered for a Hunter main, the rest is focused on pure damage skills. As a Hunter, Just Guard is such an amazing survival tool trumping all else that it is completely worth the 4 SP instead of 4% damage. It not only negates all (frontal) damage during the block, but the invulnerability lasts for a bit afterwards as well. Just Counter does the obvious thing of letting you Just Attack after a Just Guard, but simply having it actually lets you move out of your blocking animation sooner than without it, even if you didn't want to attack right away.
Sword Gear is obvious if you use more than one PA or simply run around with it for any length of time to actually build and keep the gear gauge. It modifies every PA in a different way (stronger, larger, faster) which really makes Guilty Break an effective gap closer, for example. It's optional if you only switch to it for Over End, or not at all, but those few points wouldn't help you much in Fury Critical instead unless you took Step Attack on Fighter. It's all or nothing for Fury Stance Up 2, like the Hunter sub used in other builds.
For the Fighter side, their weapons have too much overlap with Hunter weapons to be of much use, and their greatest strength is in... their strength. But using weak all-class versions cuts into your damage too much to be worth using over the much stronger Hunter weapons you can use instead, so there's not much point. After maxing the stances, Fighter can learn either Chase Advance or PP Slayer along with some extra S-Atk or Step Attack to free up SP on the Hunter side.
Braver as a subclass can be effective as well, but not as much as the stances and other skills that Fighter provides. You would also need to get very lucky or purchase a very expensive all-class Katana to make good use out of those PAs.