Peanut oil contributes long-lasting lather to a soap. It is highly unsaturated though, so it is prone to going rancid. Peanut oil is also regarded as a non-drying, conditioning oil, similar to olive and castor oils. Safflower oil is another unsaturated oil, so it should be used in combination with palm, coconut, or a similar oil. It is valuable for its moisturizing properties.
Sesame oil is good as a superfatting agent because it is very good at moisturizing.
Some people find that it can be prone to rancidity but others have no problems. It has a very strong scent which can overpower EOs, so plan your scents with that nutty sesame odor in mind. It makes a softish bar so use it in combination with other, more saturated oils. Shea butter is a truly superior superfatting agent because it contains a large percentage of elements which do not react with the lye, but instead remain in the soap to nourish your skin. Vegetable shortening is often made out of soybean oil.