This is tough one to decide. Wick has a far greater quantity of feats and more impressive displays of endurance, but Moses' feats show him to be far smarter, more experienced, and overall more efficient. I suppose we could compare Zero to Han, two highly skilled martial artists regarded as the world's top assassins, but it's difficult because neither Wick nor Moses beat them in straight up matches. Zero essentially handicapped himself, giving Wick a chance at victory, and Han forfeited the fight to help Moses save the world.
Can we get some further arguments?