I'd say it's too early to make that judgement. Overall, I LOVED the Avengers. However, after I saw TDK, I had to rewatch it again that same weekend. The Avengers I will see again in theaters, but I've given it a couple weeks. Also, I know I loved TDK enough to watch it like 10 times over the past 3 years, I don't think I'll feel the need to do that for Avengers. Also, good as it was, I think I even rank it #3 behind TDK and X-Men: First Class. I consider First Class somewhat underrated.
But I will mention that I prefer time spent on plot and dialogue to explosions - so while the Avengers were good all-around, TDK and FIrst Class were better written (and acted) from the ground up. Not to take away from the acting of Avengers, which was also top notch.
