Truth be told, neither one is my type. Although I've found various blondes and/or redheads attractive, I prefer women with dark hair and eyes (in a perfect world, caramel colored skin, too).
That said, gun to my head, in their primes, I'd pick Amanda over Hillary. More than anything, I am disputing that Amanda was never in the top 10 of Nickelodeon chicks. IMO, she is.
Duff is hot, no doubt. Not saying I would not inseminate various cavities on her person, but Duff is too short and dwarf like for my liking (licking?). Amanda projects taller and, IMO, the girl-next-door sexiness which Duff, outside of her youthful/"jail bait" Lizzie McGuire days, cannot attain. Again, just my impression/opinion.
Maxim and the like can make any 6 look like a 9. Hell, they even made Rachel Ray look hot for 5 seconds.
Regardless, you always struck me more as a London Tipton fan.