Goblins are difficult to take seriously. They're small, they're cowardly, that sort of thing. By comparison, orcs have recently assumed the mantle of noble savages - they may be brutal, violent and nasty, but many people regard them as simply filling that role. (And in Tolkein, they're mutant elves. Which makes them somewhat cooler.)
So I say goblins are the evilest of the two, because orcs can be sympathetic.