What brand of dog food for should i feed my pompek dog?

My dog used to love purina dog chow and then one day he got over it, I tried to get him to eat it he just didnt like it anymore. I give him Ol' Roy now, you can get it at walmart it has been around for ever, Since my dog Is an American Pitbull terrier he weighs 100 I buy him High performance, but agian he pulls weight compitions. Ol'roy makes all diffrent kinds.