Pompey + Maria > Bloodstorm + Maria

Pompey is one who sacrifices himself at the front lines in exchange for a OHKO or protected in back and healed by Maria.
Bloodstorm can get nicer damage as the battle goes on if you can manage to get his health low (and keep it there). Maria healing Bloodstorm is kind of counterintuitive.

Personally, for PvP purposes, I think I would prefer Pompey.