Best anime ever? That would be hard to choose. but my choice would have to be the one anime that made me think the most.
And that would be Serial Experiments Lain. It was very...weird for lack of better term. It had a generally weird concept as well.
Its about a young girl who knows nothing of computers and the wired (Internet), but a IM from a recent classmate that committed suicide saying she was IN the wired starts an evolution of sorts.
She started working on her computer. The computer slowly took over her room. The computer symbolizes her maturity. This brings another thing very prevalent in the show. Symbolism.
The show has many examples of symbolism which adds to the weirdness. It makes many who watched the show wonder..."What the fuck is going on here!" The basic concept of the show is not easy to explain, because it spoils many things.
I encourage people to go watch it. It is very interesting and not too long. It is actually hosted on youtube by a user, but I forget his name.
I've seen a few pages of the manga, but I can't say much about it, really. :|
EDIT:
http://www.youtube.com/watch?v=puARhRd1G2o
Link to first episode. Er...first part of the first episode.
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