When I play a Vampire or a Werewolf, that quality - that they are a vampire or a werewolf - is almost required to be a major part of that sim's story. Even if it's just how they manage being what they are along side whatever else is going on, a story with a Vampire or a Werewolf needs to address that vampire/werewolf lifestyle. I can't "play casual" with a vampire or a werewolf, because sooner or later the feeding or the rage is going to get in the way.
With spellcasters, I can play it casual - they learn scruberoo, maybe repario, and don't touch magic otherwise - or I can have a sim go deep and master both aspirations, have an extensive collection of Familiars and magical items, build an alchemical garden and otherwise go all in. Or I can play anywhere along the spectrum between hardly touching it and mastering the whole thing.
I've enjoyed playing with Werewolves too, and plan to experiment more with them in the future, but their stories are still fundamentally Werewolf Stories, while spellcasters can have stories were the spells are just... window dressing. Spellcasters give me the most flexibility in the stories I tell, and how intrusive their nature is in their life.
And for that reason, Spellcasters will continue to be my favorite, probably even after Faeries eventually come along.
