Definitely UYI II. Although UYI I has grown on me over time, there's still some songs on that record that are just boring to me. Like Back Of Bitch, You Ain't the First and even Right Next Door To Hell.
Sure, the alt. version of Don't Cry on UYI II is a bit unnecessary an My World... Well that's more of a tongue in cheek joke outro anyway.
Overall the songs on UYI II are just better IMO.