I prefer not to choose one over the other, I enjoy (or dispise...or enjoy dispising) both. Front squats definately hit my quads much better than back squats, but my hip and hamstring stength is more influenced by powerlifting style squats (obviously). I think anyone that doesn't utilize both is doing themself a disservice.
As for back pain, unless their is an underlying issue, generally if you check your ego, lighten the weight and focus on form it should correct itself. Of course developing a strong P-chain and abs should help as well.
To the orig poster:
Most people, including knowledable trainers, carry a bias towards certain movements or training concepts. Do you know why the person who gave you that advice holds the opinion?