Well if you do rc all you get is rc xp and a bit of money, But if you were to do slayer you would get Slayer xp and Atk,Str,Def,Hp,Magic or range xp as well. Plus the many drops of seeds, herbs and charms that cane be used. So over all if you do rc you train one skill but if you do slayer you get the opitunuty to do up to 10 skills :) Edit And slayer can get you pray xp too