Hillary duff or Britney Spears?

Whom do like most? Is Britney unbeatable? or Hillary has her own way to sing and beat Britney?
What do you guys think?

To be honest i haven't listen to Hilary duff, though I used to think Britney Spears did have some interesting tunes I never considered her an excellent singer -mind you, that doesn't mean I didn't enjoy some of her work- so I can't really tell.