I like idiotic characters if it fits a parody-like or whatever concept.
Such as Keroro Gunsou and Excel Saga.
I like the clever ones too, but not the ones who pretend to be "oh so deep and intelligent", but end up being boring and cliche. Evangelion, for example, was not so bad, but it was a little bit that way.
If you want a lot of character development, I suggest anything by Satoshi Kon, Gungrave, Ergo Proxy and Lain.
And then, how about characters that are clever, but sometimes intentionally act a bit foollish? Such as Vash the Stampede (Trigun is one of my favourite cartoons EVER) or Lupin III? I find them quite charming. But now, that requires good skills to achieve it.
As long as the trend is gonna last, they are gonna make those stupid characters. But then, that's only mainstream. When has the mainstrem been any better than the underground or the "less mainstream"?
Simply, follow what's less known, then you'll find a lot more interesting stuff.
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