I'm curious as to what is the best medicine to treat really bad watery eyes?

See eye doctor: Try using artificial tears four times a day because many times the eyes water when they are dry as an overcompensation. If no relief, see eye doctor because the drain duct could be clogged.

Depends on the cause: Epiphora, or watery eyes in medical jargon can be due to a variety of causes. These can be boiled down to those that cause too much tear production such as ocular irritation and watering due to insufficient drainage of tears such as cases of nasolacrimal duct obstruction. So, the solution to the watery eyes depends on the root cause. Many good treatments exist for most causes of epiphora.