Your question has more than one answer because there are different kinds of COUGH.

Most OTC brands should work best when the cough is "wet" and sputum is expelled with the cough. These brands usually contain the DM ingredient too and should be used with caution. Google will tell you why DM should be avoided with other many prescription meds.

The other types of "Cough" medicines are actually sedatives, and contain ingredients to just relax the breathing passages a for dry coughs. Your Doc and pharmacist can help explain how something simple as a cough could actually be sign of other things going on, including medicine interactions. Many times, cough drops may be a a safer choice overall.
be Well

I use standard Walmart or Walgreen products, usually the DM version.