The only back I'd take in round 1 is Gurley if he falls from injury. He's the next great NFL back.
Miller has proven to be good enough, he's not great but he's good enough and we have much, much bigger fish to fry than a position that seems to grow on trees these days.
I'd go with either Gurley if there, a big, playmaking receiver like Green-Beckham or the kid from AZ St, a mauling guard, a good cover corner or a versatile LB.