These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Game Breaker: The Alien Arm Gun. It's a guaranteed drop every time you gib a Hulk, is a One-Hit Kill on Old Coot and Billy Ray clones, wastes a dog in three, and it's all-around powerful. Each fire action is a burst of 3 shots that only consumes one ammo, and each new arm gives you 25. You can use it exclusively and still not run out of juice for it provided you don't miss often.
Goddamned Bats: Billy Ray is uncannily accurate with his shotgun even at longer ranges. Dogs are tremendously fast and move erratically, on top of being ridiculously tough for their tier (expect to spend at least 6 shells on one, and even then all of them have to be full hits with no missed pellets).