Perhaps moved by recent events, 2ch has compiled its own chart ranking comparing the relative craziness and propensity for dubious (if not dangerous) behaviour each of the major groups of otaku find themselves predisposed to.
The diagram, translated from the original with positioning remaining faithful:
Geha refers to the “games & hardware” board on 2ch, which is host to notoriously crazed and mutually antagonistic populations of Nintendo, Sony and Microsoft fans (and is also the basis for the Neptunia games). Korea refers to followers of the “Korean wave,” and the Hanshin Tigers and Urawa Red Diamonds are both popular sports teams with at times overly dedicated supporters.
Those wondering why apparently harmless train-spotters are considered even more dangerous than seiyuu otaku and idol fanciers are advised to look into some of their previous antics.