Thankfully, the GEARS 2 guns aren't as useless as the GEARS 1 guns. But the lancer is the best.
It's very balanced for any situation due to ammo capacity, damage, accuracy, and well, that damn chainsaw. Just need like a longshot or boomshot to balance out it's weaknesses and your golden.
The worst? For me it was the torque bow. Took too long to charge for too little a result, especially if I missed. But you can contribute that to my inexperience with it, so, :p