>I'm aware I really am being a bit of a wanker
You said it,... I mean it's obvious that a book can contain and develop much more intelligent stuff than an anime or even a movie. Both media are too short to really instruct you in anything, they can at most evoke interesting concepts and strike you emotionally, but afterwards it's up to you to do the thinking, or read books. So let's not fault anime for what they can't do yes? Even if anime can't compete with books, they for sure can be more or less intelligent/dumb, and here I guess we're talking about anime that make you think a bit.
>it's honestly beyond me how NHK [...] could be classed as intelligent
This is where you lose any credibility in my book. NHK makes a pretty insightful and sincere analysis of several contemporary problems, and does this in a captivating way (at least to me). This is for sure an anime which makes you think, unless you shut yourself to it (usually by saying the main character is a moron, and discounting the anime). I mean, its BECAUSE Hamlet is a moron that Shakespear could write his play. It would be interesting to see what do you call 'smart' animes, to get an idea of what is your concept of intelligent stuff.
>Stuff like Elfen Lied, Saikano, Gantz, all of which people have recommended in this thread, are in no way intelligent.
I won't defend Elfen Lied or Saikano, since I did not find them great (and Elfen Lied much less than Saikano), but about Gantz I could comment: I hesitated to recommend it, because on the surface it looks like the mindless gore of Elfen Lied (nothing wrong with that, it's just not 'intelligent'), and has apparently the same exponential syndrome of DBZ and many other shonen. That's why I used many negative comments in my recommendation. But for those ready to suck it up, there is a subtle deviousness in Gantz scenario. You can feel that the script writers were playing with the minds of the viewers, and it's this which struck me. Gantz made me think a lot after I saw it, even though I wanted to beat the crap of the scenarists, while I was watching it. This being said, I'm sure many people will not appreciate it, hence the mixed comments I gave. Still, I think it's a VERY intelligent anime.