Avengers was amazing. I wasn't expecting much since I'm not a superhero fan, but I have watched it four times and still love it!
The Last Airbender was awful. I was mad that Soka wasn't funny (although, after he called our music teacher and told her that he wanted to make it funny but the director wouldn't allow it, I was fine. And yes, Rathbone is on a talking basis with my music teacher :P He used to be in my theatre group) Anyway, the director completely ruined almost every aspect of it. The only thing I like was Zuko. I don't know, but I just liked how he played it.
I would never go back to watch The Last Airbender.
So, yeah, I think the Avengers was 150% better then The Last Airbender.