Dog food help?!?!!?!?!?!?!?!?!?

Ok well, my mom went out and bought my 3 month old puppy Bil-Jac dog food. He LOVES it. But I did some research and found that its not good. :/ So I bought him Blue Buffalo and he eats it a little bit but he doesn't like it and sometimes refuses to eat anything except Bil-Jac. Is it ok if he just stays on Bil-Jac? I'm very reluctant to let him, but if he likes it. Help?