To many Pathfinder is the heir-apparent to the legacy of D&D, to others it's the biggest retro-clone out there. But regardless of how you view Pathfinder, one thing is for certain, it is wildly successful.
Pathfinder also has it's own witch class from the Advanced Player's Guide. It is nice and has a cool vibe about it, there are somethings I don't care about it. I talked about it detail here, and offered up a couple of Prestige Classes here and here.
Other companies though have filled the gaps with their own Pathfinder-compatible witches.
A Necromancer's Grimoire: Secrets of the Witch
For a fuller witch I would also grab The Book of Faith (spells) and Paths of the Druid (for some Prestige Classes and ideas for familiars).
Advanced Feats: The Witch's Brew (Pathfinder RPG)
Certainly one of the more interesting books for the new Pathfinder witch class. You will need the Advanced Player's Guide to get the most of of this book obviously.
We start off with a brief overview/analysis of the witch class. Not bad really, but nothing we can get from the APG.
On to the meat of the book, the 30 new feats. They are a mixed bag, but for the most part they add a lot flavor to the witch. There are some familiar affecting feats which is nice, and commentary/sidebars on a few.
There are also 3 sample witch builds that you can use to make your own.
Witch Spell Cards for the Pathfinder Role Playing Game
Exactly what is says on the tin. Spell cards you can print out and use with your Pathfinder APG Witch.
If you like cards then these are great. If you prefer sheets then they can still be used.
Paths of Power
Described as a source book for Base and Prestige Classes. This book features a new Witch class. This witch has "Circle" magic and gets spells based on Wisdom as do the witches in the 3.0 book I did years ago. This witch is a nice alternative to the Pathfinder Witch. If you were to use both I would call this one a "Witch" and the APG one a "Warlock". In addition to the witch we get the Anti-Paladin, elemental wizards, gladiators, samurai and the Voyager. NPC classes include the Courtesan, Captain and Sycophant. Truthfully I only found the Courtesan useful. Prestige classes include the Child of Bast, Crypt Stalker and the Envenomed. Personally I would have liked the PrCs to be a little more related to the base classes.
There is though plenty of magic items and spells. There are also plenty of new witch-related feats.
Since I bought it for the witch alone, I am actually pretty satisfied with what I got.
Book of Arcane Magic
Another great book from 4-Winds Fantasy Gaming. This one focuses on the Arcane Spellcaster in Pathfinder. While the book predates the APG Witch, a lot of these new spells and ideas can be used with the witch. Of course they are all also fine to use as they are. In particular I liked all the new Sorcerer bloodlines and colleges of Wizardry. I like the idea of my wizard doing post-graduate work in magic.
There are new familiars, spells and magic items. So it is worth it just for these.
The Book of Divine Magic
Likewise, the Book of Divine Magic adds more material to your cleric, druid and paladin classes (and Rangers). There is a list of gods and their domains. Plenty of new spells. Rules for temples and divine animal companions (like familiars) and new magic items and relics. Avery densely packed 94 pages.
Up next are a the "With a Bullet Point" series on witches from Super Genius Games. Designed to be quick guides that can be used with a minimal of prep time and minimal cost. I like the idea.
#1 With a Bullet Point: 5 Magic Witch's Daggers
Here we have 5 magical Athame ("ath-a-may") or daggers that can be used by witches. These weapons work in conjunction with the witch's hexing ability, though they can be used as magical weapons as well.
Short, sweet and to the point. There is nothing to complain about here.
#1 With a Bullet Point: 13 Witch Hexes
Again one page, one buck. This time we get 13 hexes that can be used by the witch. Some blur the line between what could be a hex and what could be a feat, but all in all they work fine.
#1 With a Bullet Point: 9 Witch Hunter Feats
Hard to mess with a good thing. A page for the cover, a page for the OGL and then a page of nine feats for Witch hunters to either protect them from witches or to help them when battling the forces of darkness. If you enjoyed the Genius Guide to the Witch Hunter (below), then this is a great addition. If you don't have that you can still use this product.
Super Genius Games also produces the "Genius Guides" which are larger and go more in-depth.
Advanced Options: Witches' Hexes
This book surprisingly has no overlap with SGG's With A Bullet Point: 13 Witch Hexes. The hexes listed here are all new and there also Major and Grand hexes detailed. There are even some hex-related feats.
The Genius Guide to the Witch Hunter
Where there are witches there will be witch hunters. This is a full 20-level class devoted to witch-hunting. Plenty of powers, abilities and feats are detailed. I think this would have worked as a prestige class, but this is pretty good.
Legendary Levels II
This book, like the first LL, deals with Pathfinder "Legendary" Levels, of levels 21 to 30. What 3.0/3.5 called Epic Levels. I think they picked "Legendary" as not to confuse it with D&D4. There is a Legendary Witch in this book, which is why I got it, but the rest is pretty good as well. In particular I liked the Legendary Samurai and the Dragon Lord prestige class. I Would have enjoyed seeing more prestige classes myself, but the book's focus was "Legendary classes" and note really prestige ones. Plenty of new feats and I REALLY liked the art in this book. So at the end of the day it was worth it to me.