If yarrick was a pick I would pick him but since he is not I would go with gaz

Yarrick? A measly human? Bah!

Yarrick is a worthy oponent to all that stand against him especially those pesky orks

Take Creed instead of Yarrick. Hide a Baneblade under his cape. Or inside of his cigar.

Nobody will see it coming

CREEEEEEEEEED! - Abbadon the Despoiler, now short of two arms

Lord Castellan Ursarkar E. Creed, Lord General of Cadia, Protecter of the Gate, Saviour of Tyrok Fields and Imperial Hero

The only man capable of hiding a Reaver Titan behind a lamp post.

On a second thought, let's not forget Ciaphas Cain, HERO OF THE IMPERIUM

I have to go with Abaddon only because the Choas Gods favor him so much. Thought there would be incredible damage to him as a result. Or any victor for that matter.

Most likely all of the mighty warriors would die in the epic clash...