Fun!

I like a lot of the -mancers too (and apparently the letter n), like cognomancer, and optimancer (mostly because it's so close to optimizer). I think my favorite on your list is cognician.

To throw in some more...

(From the Greek "Nike" for Victory (or, winning):

• nikosopher

• nikomancer

• nikologist

From Aletheia (Greek for Truth):

• aletheisopher

• alethologer

From Veritas (Latin for Truth):

• veritician

• veritosopher

• veritimancer

• veritologer

From ingenium:

• ingenian

• wingeneer

And others:

• noomancer

• noocian

• neostoic

I also apparently like the letter n.