Overall, I'd opt for the cornsnake being a better starter snake, based on the following criteria:

1.) cheaper initial cost (although a cornsnake from petsmart may be just as much as buying a baby BP from an expo)
2.) many of the different morphs are fairly cheap, too, so a noob has many choices to start with...compared to entering BP morphs ("hmmm...$40 for a normal BP....$150+ for anything else....not a hard choice!")
3.) better initial feed responses (usually)
4.) less demanding care/husbandry

...like someone else said though, the only thing I don't like is perhaps a baby corn is quite small and squirmy compared to a more "hefty" baby BP. However, if they eat good, it doesn't take long for a baby corn to get large enough for regular handling.