I like the one in Magic. Mainly because it's the oinly one I have, but it does the job I need. I don't need a full book devoted to the witch. With Magic I get everything I need plus rules for other magic types.
You're missing the Witch from The Hunt and the witch from Way of the Witch from Citizen Games.
So far I think GR's from the Witch's Handbook covers it best. Never liked witches that could cast fireballs and prismatic sprays. The Hunt would be up there too but the Q. Witch has a lot of other goods to it while the Hunt is mainly a functional core class.
Presently I have AEG's Magic and the Green Ronin Witch book, with the Mongoose book on order.
I like the feel of the Green Ronin Witch, but the spell list is too small and leaves me wondering what to do about other d20 sources.
I like the AEG Witch but doubt I would get the on the fly magic past my DM. As well I don't like that the class has no 'features' as it levels. I like to see 'features' in a class list even if they don't really do much as they make you feel you're getting something for staying in.
I hope to have the Mongoose book in a day or so.
I've never seen the 'Slaine' book up close. Saw it in the store and put it in the category of "setting or module" which is my 'don't usually buy' list.