While looking at various choices for Squinty_Eye's Pathfinder play-by-post game I started reading into both the Witch and the Inquisitor.

I've not played either in Pathfinder, and in fact not played a class like them in any Tabletop RPG, and was wondering if anyone has and could give a summary of the experience.

Thanks in advance!

Witches are fun. Also, fun fact: If you play one, you'll be referred to as a "shaman" since "witch" carries heavy negative connotations.

~SE++

Do you mean in your world? Or in general?

How does their spell casting hold up against other caster classes like the wizard?

Everything will be relative to my world, but there's a few things that people tend to do in them:

(1) A Witch is referred to as a Shaman
(2) A Rogue is referred to as an Infiltrator
(3) A Wizard or Sorcerer is referred to as a Mage
(4) A Bard is referred to as a Gypsy

As far as spellcasting goes, a witch has the same choices on spells per day and spell levels as a Wizard. Essentially, a Witch is pretty similar to a Wizard except for a few things:

(1) Instead of a Spellbook, they have a Familiar (both are studied daily for spells)
(2) Instead of an Arcane Bond + School, they have Hexes

Aside from those two major differences, they play out almost exactly alike for stats.

~SE++

Ah, well I was asking in general, not specific to any particular world set.

Just curious if anyone had actually sat down and played one to a decent level, and to see how it faired in the overall party balance.

I've found it pretty balanced, but the threat of losing a familiar and all your spells is a little scary. Usually, when I play a mage, if I'm any decent level (usually 3 or higher), I'll make a backup spellbook during the downtime roleplay and store it. A witch can't do the same for her familiar.

~SE++