Lol...the Collector "Well...he's a pimp"
Can't argue with any of those. I could see the question "What about the Peoplebusters?" but the Anti-Ghostbusters represent the same niche more or less.
The favorite of mine that didn't make it was the Master of Shadows from "Slimer, Is That You?" Had that great cool look a lot of RGB villains had, and some great interplay with him and Egon. Not to mention being the first Class 7 with his own interdimensional answering machine--how awesome was that?