I consider Bowser Jr. a Koopaling. And a dang good one at that. Maybe I'm just biased because I'm also a baby brother. :P
Anyhoo, here are my rankings. Nobody is hated and all eight are loved btw.
First Place: Roy "Roy-boy" Koopa
Second Place: Lawrence "Larry" Koopa and Bowser "Bowsy" Koopa Jr.
Third Place: Ludwig von "Luddy" Koopa
Fourth Place: Lemuel "Lemmy" Koopa, Ignatius "Iggy" Koopa, Wendy Olga Koopa, Morton "Morty" Koopa Jr.
Bowser Sr. is above them all, though, because he's BOWSER, BABY

No regrets for the fanon full-name thing.