Personally, I thought the Scorpios was the most interesting hybrid. Its venom and ability to self replicate made it more unique. Plus it really gave off an unsettling "abomination of science" feel. Looking at its appearance and the way it acted and moved, it really came off as something that shouldn't exist in the natural world and that the fact that it was made is an affront to nature, something that isn't an animal, but a monstrosity, which is something I really wanted to see with the hybrids, which we kind of got with the Indoraptor, but not so much with the Indominus.
Also, I wouldn't really count the Spinosaurus as a hybrid. Canonically it is mutated and was a result of a secret experiment, but it was still meant to be based on a real dinosaur and at the time it was created (and when the film came out) it was accurate to what the animal was thought to have looked like, even if the reconstruction is considered outdated now. I would argue that the Velociraptors are more of a hybrid than the Spino, considering that they're over twice as large as real Velociraptors, featherless, and based more on Deinonychus, but even then a lot of that was based on certain information at the time the original novel and film were made.
