So, my group and I have been discussing the witch, and we feel that witch may actually be better suited as a wisdom caster.
Three reasons for this:
1) Wisdom gives the witch a niche. As it stands, not too much separates the witch from the wizard. As another intelligence-based arcane spellcaster, the witch runs the risk of stepping on the wizard's toes if in the same party. Using wisdom would differentiate game play, especially when it comes to skills, between the two classes. Also, the secondary ability score of the witch, as it is for most spellcasters who don't want to die, is dexterity, and, currently, there are few Wis/Dex character classes.
2)Wisdom is atmospheric. I can really imagine the witch being better at skills like sense motive and perception, than he is at spellcraft. It lets the witch be more spooky.
3)Intelligence implies that the witch studied their craft thoroughly like a wizard. However, under the current description of the class, the witch does not have a solid understanding of where his power comes from. Indeed, some witches apparently have no idea. A wisdom-based caster derives his power from the belief that something else is granted him power, which seems more in line with the current description of the witch class.