the only thing I hate more than manga series with 150+ chapters (yes, I hate Naruto, One Piece, Bleach, all of those), are manga series that have 150+ chapters and shit endings.
I'm talking about crap like To Love-Ru and the original Code Geass. I'm talking about crap like Tsubasa Reservoir Chronicle and Video Girl Ai.
Endings you thought sucked / you hated?
and yes, manga only. All anime endings suck because they cut straight to the ED Theme which is always a shit song.