Any of these worlds would mean I would have to play by the same dimensional rules. I.E, I go to Tamriel, magic works. I go to Capital Wasteland/New California Republic, stimpacks work. Therefore, I'd have to choose a place where healing mechanics aren't easy (c'mon, Rapture naysayers), and dying is certainly a problem. Therefore, I'd say Borderlands...world. I'd rather not fight all the time, and having nothing but a random dude with a gun and a leveling system come in once in a while to clear out the baddies is not what I'd have in mind for protection. I'd try to be a vendor, because there's only so much fighting I could take in my day, but there's not enough customers, and the vending machines would undercut me so bad I wouldn't be able to start a decent business. So...I'd say that would be the real worst.