Generic demon girls vs. succubi, who's better? The way I see it, is:
>demon girl
>does not directly steal your life force during sex
>which is a good thing
>however, she is more likely to corrupt you and/or ruin your life so you would sign your entire soul away into eternal slavery for her
>MGE demons are only marginally better in that their ultimate goal is to make you their permanent lover, so chances that they intentionally try to ruin or hurt you are zero, but they still use the same tactics and attitude
>and once you're in bondage to a demon, your life entirely depends on her whims
>succubus
>steals your life energy through sex
>however, it's a one-time deal
>you pay a small amount of your life force to have a good time, and possibly whatever other perks you would want her to grant to you
>in MGE and settings like that the harmful effects of such energy drain are minimal to nonexistent, and the energy exchange is actually bilateral
The way I see it, succubi win clearly in both cases.