Just about few hours ago,my friend and i argued about which theory is the best theory nowadays ever existed. I claim that string theory is the only game in town as what i heard from Dr. Michio Kaku's TV shows, while my friend strongly disagree with it. He claimed that quantum theory is the best theory which agrees with experimental results whereas string theory is just a theory without any evidence. Is that true about what my friend just said? Are there any experimental proves for the sting theory (or even m-theory) till today? Which theory describes the entire universe better? Quantum o String?