Which treatment works the best and fastest for upper respiratory tract infection?

Cold: There is no treatment that works particularly well for the usual upper respiratory tract infection. The vast majority of these are caused by viruses for which there is no treatment. You are treating only the symptoms (runny nose, mild cough, feeling yucky); the otc cold medications help some with these symptoms, and are ok to use, but they are not a cure.

Dr Villaplana agreed

Viral URI: Most upper respiratory infections (URI) are viral. Treatment is supportive and most people can be cared for at home. Supportive therapies may include cool mist humidifiers, encouraging hydration, medicines such as Acetaminophen or Ibuprofen to treat fever. Other over-the-counter remedies are available but should be used with caution. Certain patients if very young or ill, may medical attention.