Watched Avengers on blu a couple hours back, picture quality was excellent but the real treat was the surround sound. Boy, it sure gave the speakers a workout.
For characters, my favourite is definitely still Bruce Banner by a longshot, Hulk second (they count as different, right? xD). I liked the way Banner carried himself throughout the entire film, and I continue to be impressed by Ruffalo's portrayal of the character. His out-of-the-way demeanor is perfectly suiting. Oh, throw Loki in there too, he's awesome.
For my least favourite - and don't slaughter me for saying this - it's probably Captain America. His casting was great; Chris Evans rocks the role... But I just found him to be boring, not of much use. The fighting he did in the helicarrier battle seemed a bit lame; I saw him kicking people and spraying a gun and thought, "really?". Even if it did keep the agents off Stark's fixit act, I couldn't help but feel like he was a slight drag on the movie.