I don't like to write lists with orders for these types of things, but a lot of the people already mentioned such as Roberts, MDM, Savage, Piper, Flair, Hogan were world class in this category. The list could go on forever in all honesty.
It was a really special time as far as personalities and promos were concerned, you even had some brilliant managers/mouthpieces like Bobby Heenan. Basically everybody could add something. Hell, even mediocre mic workers such as the Ultimate Warrior were entertaining to a certain degree.
Having said that, I'm not sure exactly how much should credit should be given to the pure talent (obviously a fair bit though) and how much of the brilliance was down to cocaine and other substances