Phil Hartman was hilarious as Admiral Stockdale and Ed McMahon. He ranks up high in SNL alumns IMO.
Phil had a TON of great characters. Frankenstein.... Unfrozen Caveman Lawyer.... RIP Phil.

I always broke up over Kevin Nealon's Mr. Subliminal, and when he didn't get too obnoxious Adam Sandler had some great ones as well (I loved the trio he did as Opera Man with John Lovitz as Opera Man's brother, and the third chick as their sister).
If the late-70s/early-80s was the Golden Age of SNL, The early to mid-90s was its Renaissance.