What do you think is the worst (Or just your least favorite) anime chliché?

Your cliche is certainly one I'd agree is problematic. I could pick quite a few, personally. The last minute arrivals saving a character really get to me. Along a similar vein, I have a big problem with powerful characters conserving their strength for no conceivable reason beyond making a fight seem more interesting to start.

Probably the biggest problem for me, however, is the "gotcha" deaths. Fairy Tail, Naruto, and Bleach have all done this. A character, for all intensive purposes, dies. No, I'm not talking about a character taking a lot of damage and appearing dead, I'm saying that there's a certainty of death. It looks like a game changer, something that will be groundbreaking for the series. Then they revive them. Whether it's Ultear, Pain, or Ichigo's inner hollow, watching characters die and then come back to life just irks the hell out of me. Watching a series treat itself seriously for once and then immediately pull the rug out from under us is one of the worst cliches I've seen, and it's all too consistent across series.

P.S. Yes, I realize that there are other examples, with shows like Yu Yu Hakusho being other blatant cliches, and Dragon Ball Z making all of these look ridiculously small by comparison, but I wanted to focus on the main shonen here.

The stereotypical anime main character is probably the worst cliche I've come across. Any character that falls into the same vein as Ichigo Kurosaki signals the anime turning pretty shit in my opinion.

It's basically the fiery, slightly idiotic, reckless, all powerful characters that really irk me. And a lot of anime's are guilty of this. Dragon Ball Z, Bleach, Naruto, One Piece...the list goes on.

All the cliches that have been listed thus far in the answers and the question description do not bother me. If they are funny and portrayed well, I actually like the goofy main characters that don't give up - especially Naruto (though I have a feeling this is not a popular view). In fact, Naruto is one of my favourite anime characters of all time, yet everyone always bashes him. Maybe I'm just weird, I don't know.

The cliche that annoys ME is the big boobs cliche. Well, it's not the only one that annoys me, but it's the first thing that popped into my head, so I'll stick with it as the one to rant about this time. Fanservice in general usually irritates me, though not always... if there's just a little bit for the sake of humour, I'm fine with it; but if in pretty much every episode large breasts are referenced, or accidentally squozen by the main character who then gets wacked by the main female protagonist who suddenly grows pointy teeth, etc, it really begins to tick me off. Examples of anime where I get sick of this sort of thing would be Magi: The Labyrinth/Kingdom of Magic and possibly even Kenichi: The Mightiest Disciple. If they're really good anime in other respects, I'll watch them of course, but it still vexes me.