Definitely the Chaos Toss. For some people, they have trouble using poison weapons like Chaos Toss. Got about 5 kills with this weapon. Or, combine with Gravity Well, then it drains a lot faster. What's your favorite weapon???
My favorite weapon in BBG is probably the O.C.O Gauntlet. Especially with equipped Damage +2 and Explosions +2, I can take out lower health bears like Snipers, Huggables, and other Olivers. Plus, at close range, I just spawn my three orbs and use Jump and SW Boots to avoid the explosions below me. If a bears survives my explosions, I take them out with TNT Launcher. Thus, the Gauntlet is my favorite.