I personally use Ahmose for PvP situations over Queen Penth. For Heroics or Quest, I used Penth over Ahmose. Penths skill makes her great for bosses, and lab for that matter. Ahmose's shield, in my personal opinion is better suited for PvP as a tank than Penths, with the high crit runes and saintings some people have she just doesn't have enough HP in most cases to survive long enough as a PvP tank.