Drake, I know Chomper's parents are hardly villains at all, but I didn't want the villain choice for the 5th movie to be that swimming sharptooth. Not enough of a bad guy if you ask me.
And Tiger, I agree with Rinkus and Sierra being the most sinister villains after Sharptooth. I found them the biggest threat. Ichy and Dil would be a threat, too, if they weren't pretty much the silliest LBT villains.
But Sharptooth beats everyone else in quality. He oozed the perfect villain--menacing, ruthless, pure dinosaur and almost unstoppable. I loved how he didn't talk. It made him scarier.