Composite bows or Crossbows because if you craft one with PvP stats you can still sell it.
Seriously though a decent Composite bows with high mana leech would be most effective with the Armor Ignore but it does depend on template. For example I used to play a Chiv/Archer (with no bushido) and I used to get CRAZY dps with a repeater crossbow just because it was fast and the Chiv boosted my damage high enough, but with Bushido that'd be a poor tactic because you wouldnt be able to reliably keep up with the shots.
As my first point states when making any weapons for PvM, if you can, make a PvP viable wep because you can occasionally strike gold. So Crossbow or Comp bow. But I'd lean toward the Comp bow for the AI in PvM.