I'd rate the characters on a slightly different scale, assuming you're using every film.
Jim:
Kermit ****
Dr. Teeth ***
Rowlf ***
Waldorf ***
Chef **
Newsman *
Link Hogthrob *
Frank:
Piggy ****
Fozzie ****
Animal ***
Sam the Eagle ***
Marvin Suggs *
Richard:
Scooter ****
Janice ***
Sweetums ***
Statler ***
Beaker **
Dave:
Gonzo ****
Zoot ***
Bunsen **
Beauregard *
Jerry:
Floyd ***
Camilla ***
Robin ***
Steve:
Rizzo ****
Lips *
Bill:
Pepe ***
Clueless *
You were right about Jerry having no "A-list" (so to speak) characters, though. It's too bad, because Jerry's characters are some of my favorites.