This is REALLY tough, I'd go with Bell but not by much. Kunis has that exotic sexy thing going but Bell has the girl next door with a bad side thing going....Dam HARD choice.
Mila Dark eyes and hair. Reminds me of another pretty lil lady. She looked real good in that movie. Forgot the name of the movie. The one that was not her fun bags.
Kunis also has that man hips thing going. Sort of an underdeveloped, unhealthy looking body. Maybe I just like 'em thicker. I can see how people like her eyes but for some reason, I don't find her face all that attractive. Kind of alien-looking for some reason. Bell's body wins by a mile and I actually prefer her less evil-looking face but can see the debate there.