Hmm... My favorite fandom would be "yuri/gl" fandom, and least favorite are "kpop" and "anime" fandom.. Most kpop fan, especially army, are annoying... Not all though! Just most of them.. For "anime" fandom... Most are annoying, too.. They would just go bash other fandom because they think "anime" is the best and not respect others.. Again, not all, just.. most/some of them~
P.S. But i think almost all fandom has those types of fans(annoying, disrespectful, etc.)