All of them basically. The worst offenders are Comicfags, Shounenfags, horrorfags, and Warhammerfags.
Power level and "vs battles" are retarded by their very nature. Characters are only as powerful as they need to be for the story to be interesting, it doesn't fucking matter if its street level or cosmic. Sandman isn't good because the Endless are the gods of gods in the DCU, but because it dives with philosophy and human nature using the personifications of human concepts to explore that. Gurren Lagann isn't good because "hurr the big robot can punch universes into nothing by the end", it's good because of likable and energetic characters, in an allegorical tale of perseverance through the toughest of times and to find the inner strength to move past them.
Power levelfags take media and strip them down to a basic "strong man" philosophy, where the only thing important to them is how many universes Superman can sneeze out of existence instead of giving two fucks about the story it came from or the actual context behind it.