This has to be one of my 10 favorite dinos that I've used. It has decent damage and okay health, and its also super fast, and it's stamina is really not that bad, and it has that stun attack underwater. This makes it a versatile all-around mount capable of fighting off enemies or escaping them too.
Baryonyx are quick like Allosaurus and do just as much damage (but don't get a pack bonus). They don't use oxygen for swimming and can sprint in the water. Right click in the water does an AoE stun that lasts about 10 sec. Their 'C' is a... Taunt? They also jump and you can fire a weapon from their back.
It's like a small Allo combined with a Kapro, in my opinion. Useful on both land & in the water. Use its secondary attack while swimming to stun, attack, and harvest. Does NOT stun Cnidarias, though, so do not expect to overpower them.