Shinon > Rolf (I like double Bow)
However, the chapter you get rolf in, if you kill all enemies and then just boss abuse he can easily get lvl 9. You just have to sacrifice earning bonus experience for that level and have the patience of a God. Ive gotten him promoted to Sniper by the chapter 15 with boss abuse and some BEXP. Not to mention if you give him an A support with shinon in the game later, he dodges alot.