Even tho I am a Sword Taker, I do think Over Taker is best for missions. The last skill does monstrous damage on dungeons, and also has an excellent range.
But, I particularly never ever lost a PvP battle to one, it just sucks on that matter [His attacks are impressively slow compared to Sword Taker, and he knocks down his targets too easily].
So yeah ,
PvP-> Sword Taker
Dungeons-> Over Taker