In tests between plain corn, soured corn, and diesel-corn; nothing beats plain corn. Hogs will eat it first.

Like others have mentioned, soured or corn treatred another way will deter manty other animals from eating your bait.

Peanut butter and Black gold mixed with corn work good too. Black gold alone works good as an attractant and poured on a rub. If the bottle had four legs and two ears, boars would marry it.