For me, the order from most to least desired, and possible feature suggestions, goes...
- Witches (Spells, Potions and Charms, references to several schools of magic such as voodoo, wicca and alchemy)
- Robots (can be upgraded with humanoid disguises, along with cybernetic enhancements for normal Sims and the return of Servo)
- Werewolves (options ranging from Talbot-style hairy person to full-on dog-style real wolf and beastlike tendencies reliant on the moon's phases, can talk to dogs, cats dislike them)
- Zombies (with a Decay motive that weakens them and slows them down the longer they're up and about, renewed when they sleep in a coffin or their graves unless they hold onto a special voodoo charm. As a Plants vs. Zombies reference, they get a negative moodlet from gardening and can turn other people into Zombies by eating their brains WHICH IS NOT NOR EVER SHOULD BE AN AUTONOMOUS INTERACTION! Also, they don't spawn at random based on the phases on the moon, just whenever you're in a lot with a zombie's grave on it at night)
- Mermaids (needs to stay hydrated, gains moodlets in the water, can use a Siren's Song to help in love, can talk to fish)
- Genie (can grant wishes for friends, Wish Granting skill that guarantees the desired outcome when granting one, can sleep inside of bottles or lamps)
- Fairies (Fly Here, Fly To..., use druidic magic to commune with animals or bolster plants, shrink down to pixie size)
- Imaginary Friend (mechanically just a normal Sim with two different forms, also premade "adoptable" imaginary friends with more abstract appearances a la Foster's Home for Imaginary Friends. They don't have ANY motive decay as long as they have a strong relationship with their "Real Friend", lest they be forgotten, which is a new cause of death)
- Something New (what is there even to do in this vein anymore?)