Well, what are the goals of a melee NPC? Well, what are the goals of monsters in what's essentially random encounters?
1. To fight valiantly
2. To die gloriously
For 1 - these guys should not be DPS people. Their presence should threaten - they should attack the people who don't want to be attacked, prevent the party from firing off their usual strategies, and generally do everything but OHKO people.
For 2 - these guys should know how to take a hit, and keep standing. Random encounters that crumple like paper are boring. The NPCs need a chance to reveal their cool abilities, and the PCs need to feel like they are fighting a real threat.
I recommend Totemist as the class to use. They are super customizable, they have ways of getting tough with AC- and DR-boosting melds, they have great mobility including flight and teleportation, and they can hit hard without needing long lists of spells or abilities. They also don't need magic items (so there's no loot), don't have the damage output of ridiculous chargebarians unless you really know what you're doing, and can run away to fight another day if need be.