This article presents suggestions on how best to mimic the core class variants from Unearthed Arcana in Pathfinder Roleplaying Game.
Barbarian Variant: Totem Barbarian
Use the Totem Warrior archetype from Advanced Player’s Guide.
Bard Variant: Bardic Sage
Use the Archivist archetype from Advanced Player’s Guide.
Bard Variant: Divine Bard
The Faith Singer bard archetype from Healer’s Handbook matches the flavour of the divine bard, if not the crunch. For that, try a cleric of Shelyn with the Evangelist archetype from Ultimate Combat, combined with the Evangelist prestige class from Inner Sea Gods for the Versatile Artist boon.
Bard Variant: Savage Bard
Use the Savage Skald archetype from Advanced Player’s Guide, or the Skald class from Advanced Class Guide.
Cleric Variant: Cloistered Cleric
Use the Cloistered Cleric archetype from Ultimate Magic.
Druid Variant: Druidic Avenger
It doesn’t even remotely have the same abilities, but the Nature Fang archetype from Advanced Class Guide fills the same role. Take the Anger inquisition if you don’t mind losing the domain spells and you can rage starting at 6th level. Or, play a Wild Stalker ranger. In either case, keep a wand of longstrider handy.
Fighter Variant: Thug
Use the Cad archetype from Ultimate Combat.
Monk Variant: Fighting Styles
Use the Style Feats from Ultimate Combat and Advanced Class Guide.
Paladin Variants: Freedom, Slaughter, And Tyranny
Use the Antipaladin alternate class from Advanced Player’s Guide for the Paladin of Slaughter. Use an Inquisitor from Advanced Player’s Guide with the appropriate alignment for the other two. The Destruction domain grants the Destructive Smite power which combined with judgments can reasonably emulate the paladin’s smite. Alternatively play a Warpriest from Advanced Class Guide.
Ranger Variant: Planar Ranger
I got nothing for this one. Not surprising, as Paizo doesn’t pay a lot of attention to the outer planes.
Ranger Variant: Urban Ranger
Use the Urban Ranger archetype from Advanced Player’s Guide.
Rogue Variant: Wilderness Rogue
There isn’t any sort of direct translation, but any rogue with the right talents can make a pretty good wilderness rogue. The Scout from Advanced Player Guide and the Survivalist from Ultimate Combat are the two best candidates for archetypes.
Sorcerer Variant: Battle Sorcerer
The Eldritch Scrapper archetype from Advanced Class Guide is your best bet. There are also several bloodline choices that improve your martial abilities. Or just play a Magus from Ultimate Magic.
Wizard Variant: Domain Wizard
There’s nothing even remotely like this in Pathfinder. I don’t even have any suggestions on how to fake it.