I'm just fascinated by the sauropods. The big ones. I'm gonna go with Supersaurus (because super! Lol)

Sci Am article on how sauropods evolved to be huge over and over again

Of all the animals ever to have roamed the planet, the iconic long-necked, long-tailed dinosaurs known as sauropods stand unrivaled. No other terrestrial creatures have come close to attaining their colossal sizes.