I'm not really sure about mine, it's either Jurassic Park or Jurassic Park III. Probably Jurassic Park, because the T-rex is the main antagonist, its only a minor character in JP3.
I've also got Jurassic Park: Operation Genesis somewhere, I must remember to play it at some time. I've had it for ages and never used it, perhaps that's because I was too young. I'm sure I'll like it anyway.
So what was your favourite Jurassic Park movie?