Well, actually as a non-Southerner, I'd say there is a southern accent. It's obvious that it's from different parts of the South - Virginia is very different than Texas but it certainly isn't New England or California. A southern accent (to me) just means that it's from the southern states.

Of course, it may be the states vs regions question. I could pick out a Boston accent separate from Maine but they both have a Northern accent to me.

Probably the worst was Ewan's Down with Love accent. Just awful.