Need animated superhero Blu-ray recommendation

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I've been on a real superhero film binge lately after watching The Avengers recently and picking up the X-Men films this past weekend. I understand there are some pretty decent animated superhero BD's and I would like some recommendations as to what to buy.

I'm mostly interested in Batman, Avengers, and Superman, but would like recommendations on other DC and Marvel properties if they are good.

Thanks!