Which dinosaur is the best carnivore?

It is probably T. rex. They are pretty common and they lived to around 30 years old maximum, which is pretty good for a meat eating dinosaur. Smaller theropods probably lived much shorter lives because of the danger of hunting large, dangerous herbivores such as Triceratops and the heavily armored club tailed ankylosaurs. Because of its size, T. rex can probably muscle smaller dinosaurs away from kills.