Barbarians I'd say Invulnerable rager, especially when dipped with Unbreakable fighter for that ridiculous tankster build.
Bard-Arcane Duelist is great, but don't discount archaelogist.
Cleric-Most cleric archetypes are kind of bad or uninteresting, but I'm a big fan of the Evangelist and the Asmodean Advocate. The Divine Tactician has it's place due to the initiative thing, and the Herald Caller is great because summoning is overpowered.
Druid-Unsure because I don't play then that often, but the stupidly powerful hippo or a caster archetype comes to mind.
Fighter-Lore Warden is fine but due to the changes to fighters with Advanced Armor and Weapon Training, I'd say base fighter or Weapon Master are the best. You can do some crazy shit with Barroom Brawler and Abundant Tactics.
Monk-Zen Archer is great, but Sohei can potentially get even more attacks, since they can many shot and rapid shot with it.
Paladin-Oath of Vengeance+Sacred Servant, probably. You get a shitload of smites and a domain when you combine them. Something crazy like the Rage Domain would be great.
Ranger-I don't play rangers enough to know, sorry.
Rogue-Scout+Ninja, Knifemaster or Skulking Slayer. Most archetypes blow, but I haven't looked at non-unchained rogues in forever.
Sorcerer-Razmiran Priest is strong, but only because it's flexible. If you want pure damage, better summoning, etc, there are better choices.
Wizard-I'm going to skip Instructor since leadership is stupid, so I'd say exploiter.
Alchemist-Vivisectionist is powerful, but it's really only notable because of how badly it overshadows rogues. If you want a mad bomber you're better off with a standard alchemist, firebomber, etc. Goblins might be the best off with their two archetypes since one grants a flying mount at level one.