Shikamaru & Hiruma :D

Or Lelouch.

Light was, indeed, intelligent, but with every move that he made to hide his identity as Kira, he made that fact more obvious to the people around him. However, there were some clever plays he made that I must give him credit for. He is more intelligent than the average person, by far, but I've seen Death Note almost four times now, and L is still clearly smarter, in my opinion. :\

armin and light

or armin or shikamaru

I actually think Shikamaru is a little better than Shikaku, despite the fact that he's younger... though we don't see that much of Shikaku, so it's hard to compare them...

...Lawliet is very good, too, of course, but I don't think he matches up to the standard of Ibiki, Shikaku and Shikamaru. And Light is also a great strategist (but not as good as L), even though I don't really like him. I don't know any of the others. I should watch more Attack on Titan...