It's tough to say. Both are on teams with very little talent. However, the Pistons have a large group of veterans to help teach Brandon Knight the ways of the NBA. I would say Kemba Walker has the better rookie season, but I think Brandon Knight has much more potential. He will be an All-Star PG.
Brandon Knight. Kemba Walker will probably start his career as a role-player since DJ is the current starting point guard for the Bobcats. I don't think that DJ will be removed from the starting line-up since I think he will have a good season next year or so. Brandon Knight is a little younger than Kemba so I know he would need some developing. They both need some developing, but both point guards are pretty good and contenders for Rookie of the Year. I see both of them starting off as role-players and then maybe later they get the chance to start.