You see my pretty, witches are quite a fun and powerful class with lots of options for both fun RPing/fluff and gameplay.
Crazy Cauldron Witch
On the “double, double toil and trouble; fire burn and cauldron bubble” side of things you’ve got the Cauldron and Poison Steep hexes, which give the witch the ability to make potions and alchemical items, a plus for him/her/the team, and the ability to make poisoned food in her cauldron. For further mastery of this kind of wtichcraft, you can take the major hexes, Cook People (if you’re evil) and/or Witch’s Brew. Cook People giving you a choice from a variety of buffs and Witch’s Brew giving highly efficient potion creation. This gets really fun with the beguiling gift spell, compelling others to eat the poisoned food. (Also, you can use that spell to give other people a lot of fun stuff that’ll ruin their weekends.)
To continue down the cackling, mad, I have lots of evil toys route, the hex, Waxen Image, gives you a voodoo doll, Hidden Home lets you hide your lair, and the grand hex, Witch’s Hut, gives you a crazy animated home.
Obviously, with a witch like this you’ll want to use the Cackle hex, paired with a few of the hexes it lists, particularly the Evil Eye hex because it’s really handy.
More Optimized Stuff
For hexes that fit into the more optimized mold, there’s Flight, which gives the witch various flight abilities on a stick. Fortune, Misfortune, Evil Eye, Ice Tomb, and Agony are all excellent debuff and control hexes. If you need healing there’s Minor Healing and Major Healing. Retribution can be a helpful way to punish enemies that attack you and your party. Prehensile Hair gives you another hand, which is always handy.
For the patrons, it’s really up to you and what flavor you want your witch to be. For more optimized patrons, the Deception and Trickery options from the APG and the Time option from UM are excellent.
For spells, keep in mind that while the witch is an arcane caster in origin, the class does have access to some traditionally divine spells, like healing. The spell list is powerful and suits the needs of the witch. Whether you’re controlling the battlefield with black tentacles, changing your age with threefold aspect, or causing break outs with pox pustules, there’s a lot of enjoy from that spell list. Since the witch is a preparation-based caster, you can learn all the of the spells on the witch’s list, given time and resources, the the options are nearly limitless.
The four archetypes in Ultimate Magic give the witch some interesting options. The Beast-Bonded archetype is familiar mastery archetype and eventually gives the witch an ability allowing her to cheat death. The Gravewalker gives the which more necromancer-y flavor, being able to control undead and getting a disgusting and creepy living doll, the Spell Poppet, instead of a familiar. The Hedge Witch is a healer witch. The Sea Witch is a, well, sea witch. More archetypes can be found here, which includes a planar specialist witch, a hair specialist witch, and an ice bitch witch. (Also, there are more hex options there as well.)
It bears mentioning that the magus has an archetype that allows the them to gain hexes. This magus, the Hexcrafter, trades the spell recall ability for the ability to use the hexes and gain some additional spells, all of the curses in the game (and a special arcana that lets you use them with a melee attack). It’s a really fun option if you want to go the warrior mage route with a bit of the ol’ hexblade feel, though better, because the hexblade was pretty weak.
Closing Maniacal Laughter
So, I’ll close with some links to guides. These are mostly for optimization, which is fine, but I generally prefer to make unique characters over min/maxed characters (which is why, above, I never mentioned the Slumber hex, which is broken, IMHO). They’ll have lots of information, ideas, options, opinions, and so forth.
Thanks for the question!