I think I liked Messiah best myself. The Duncan arc was compelling (and let's be honest, who doesn't want to knock boots with hyper-sexual space nuns?) but nothing beats House Atreides' first triumphs on Arrakis.
And what he did with Paul after he won everything is nothing short of brilliant.
And the Tleilaxu epigram is in my mind often
Here lies a toppled god
His fall was not a small one
We did but build his pedestal
A narrow and a tall one
Which is applicable in so many situations in real life.
