All god swords have identical stats the only difference is the special in which the Saradomin god sword heals you and restores prayer depending on how much damage you inflict using half the special bar. The Armadyl god sword Special increases your damage by 25% also using half the special bar though it cost more. The Zamorak god sword should just be out of the question though cheaper its special freezes your opponent which is rather useless when using melee. I prefer the Saradomin god sword for pvm (player vs monster) and for pvp (player vs player) I'd prefer a Armadyl god sword.
