Toxic Guns
The Toxic Guns, by themselves, are not very good weapons. They kill slowly, they have bad range, and their accuracy isn't any better. However, throw on that Shadow Hunter Braid, and the Toxic Guns take a huge boost in damage. You can kill enemies in just a few shots with this combo, and you can do the same with the Darkness Combo Guns and Haunted Guns.
So which one of the three Monster Mash weapons you use is entirely dependant on which one you like the look of the most and which ones you own if any - the three Monster Mash weapons are exactly the same in terms of damage and range. Of course, this is assuming that you have all three; if you don't, buy the Shadow Hunter Pack over this one as the Shadow Hunter gear is better than the gear from the Warlock and Monster packs. The weapons are the same, but why buy the Monster or Warlock Gear when you can have the Shadow Hunter Pack?
So really, the only reason you'd buy the Monster Gear is for the looks. The Shadow Hunter Gear is better otherwise.
See my Darkness Combo Guns review for a more in-depth look at the stats of the Monster Mash weapons.
So which one of the three Monster Mash weapons you use is entirely dependant on which one you like the look of the most and which ones you own if any - the three Monster Mash weapons are exactly the same in terms of damage and range. Of course, this is assuming that you have all three; if you don't, buy the Shadow Hunter Pack over this one as the Shadow Hunter gear is better than the gear from the Warlock and Monster packs. The weapons are the same, but why buy the Monster or Warlock Gear when you can have the Shadow Hunter Pack?
So really, the only reason you'd buy the Monster Gear is for the looks. The Shadow Hunter Gear is better otherwise.
See my Darkness Combo Guns review for a more in-depth look at the stats of the Monster Mash weapons.
Tl; DR
Shadow Hunter > Warlock and Monster. Get the Shadow Hunter Gear if you're looking for the best bundle.