I like them both. But Vamps win. In a vacuum and in all other sim games I prefer witches/casters but in sims 4 vamps are better. Casters in sims 4 make the game too easy. One of the first portions fill all needs and only require an apple to fill a sims needs. I got a max level caster with all spells and potions in two sim days without cheats. Casters have minimal or no downside to balance their power. They're too easy to master and play. They take all the challenge out of a game that lacked much challenge to begin with. This is not a good thing.
I am glad to have the choice and like both. Heck I like all the occult lifestates. But vamps in The Sims 4 are better balanced as they offer more replayability as they add challenges to overcome, take longer to max, and aren't all upside. I maxed 3 casters now with zero death, zero curses and even if they do happen familiars save you from death, and curses are easily removed. There is no game balance to sim 4 casters none. This is why I vote Vampires in this game, even if I prefer casters everywhere else.