Of the pre-prequels (Butlerian Jihad), the prequels ("House...") and the sequels, the only ones I'd even remotely suggest you bother with are the prequels. And even then... meh.
Maybe I'm not being entirely fair - some of the ideas in the KJA/BH books aren't half bad. They're just poorly executed when you consider what came before.
Hey, that sounds familiar...
DE