It doesn't make too much sense to ask for the favorite of a species including characters so totally differently presented as Chomper or the original movies Sharptooth. People would favor Chomper for very different reasons than they might favor the original or one of the other sharpteeth who are presented as mostly anonymous villains by natures design. If it comes to impressive, intimidating "villains" the original sharptooth would probably be number 1, with LBT 9's Liopleurodon in hot pursuit. Chomper's parents, the LBT 5 sharptooth (I think that one was supposed to be a Giganotosaurus rather than an Allosaurus), the LBT 6 sharpteeth (there we got an Allosaur) and the raptors too could qualify as somewhat impressive, but all of them were subjected to slapstick (so was the LBT 9 sharptooth, but he retained more of his "dignity" through it). The sharpteeth of LBT 10, 8, 11, and 12 were almost offensively harmless dinosaur kid toys.