For newer ones:
Lil' Dani Moonstar can get pretty slutty once she's been properly broken in.
She can be found at Walgreens, along with black Emma Frost, who while having smaller boobs then she should, make up for it by having one of the best non movie face sculpts/paint jobs right behind Scarlet Witch from the Magneto family set.
You also might be able to find Magik and Sue Storm there as well.
Comic Elektra from the SP//DR wave is pretty hot.
Domino from the Sasquatch wave actually has a very cute face.
Blink from the Caliban wave looks nice.
Boom Boom from the Windego wave is great if you're looking for a 80s/90s gal.
For older figures, there's the Black Widow from the Mandroid wave, along with Maria Hill from an Agents of Shield box set. They use the same body mold.
There's also Elsa Bloodstone, but she was in an expensive box set.
I've never found the updated Gamora or Nebula from the Mantis wave, so I have no idea how good they are.
Hela & Peggy Carter are more Mommy Doms, then sluts, but still plenty hot.