I actually voted for two because I couldn't decide between them.
Originally, I would have gone with the T-Rex species solely because the original Sharptooth left such a menacing impact on me that I would have nightmares as a kid. Also, being a Power Rangers kid I always wanted to be the Red Ranger, and seeing as the dinosaur was T-Rex, that helped me like it even more.
On the other hand, there is the fast biter species. Not counting the TV series, we haven't really had that much exposure to fast biters, besides LBT III and LBT XI (correct me if I'm wrong). I thought they were cool, but not my favorites. Then I saw Jurassic Park, and holy **** the scene with the two Raptors in the kitchen is so scary! That boosted my liking of that species so high.
So because I can't choose between the two, I voted for both of them.