I personally prefer Spellcasters, and pretty much always play as one. However, there are a few disappointments as far as I'm concerned. With the potions, I hate how the cauldron is so huge, yet only makes 4-6 potions, and each vial is only a single dose. Also, I'd like to be able to mix potions together, and even add them into regular food and drink. I was also hoping to be able to enchant a few everyday items around the home, too. Not use magic on them, but make them magical with enchantments. It would be nice if with Delicosio and Herbio you could select the food or plant you want to conjure, and add some drinks, too. Also, being able to choose what you turn someone into with Morphiate. And cast some spells on the home. A magic staff would be sweet, too. And why can't we sweep our homes with brooms? Summon lightning with Zipzap after being struck by lightning, being able to strike any one or anything, and supercharge turbines (without being hit by lightning first, though). And creating temporary clones of other Sims. And learning the Rite of Dissolution spell.
As for all Occults, I'd like to see them involved with education. Let's go to Spellcaster School so we can learn some spells that way! Or some optional rabbit hole lessons that work similarly to the skill classes from Discover University; go 5 or so times and earn yourself 1 shiny new spell or potion recipe. And Occult careers, damnit!
On an unrelated note which I hope I won't be getting in trouble for bringing up, I'm new to the forums; does anyone have any tips to increase my ranking so I can make my own threads?