The Yutyrannus is an amazing tame, especially in a group of 3-6. Its stat-boosting roar is overpowered if you have buddies with you riding the other ones, because if they all roar, it can result in a massive stat boost!
This thing is an absolute beast. I tamed a level 120 and pumped nothing but stamina so it could yell at my dinos to do better when fighting the broodmother. They were so inspired, that they got a 25% damage bonus, and a 25% damage resistance bonus meaning we completely shredded the broodmother when it may have been a close fight. One or two of these behind your army and you, my friend, have comrade stalin himself telling your troops to fight to their last breath
Once tamed, upgrade stamina if you chose a low level individual. Their roar takes a lot of stamina, so higher levels are recommended. If you can get a lot, you can position them surrounding your base, and they will roar at any attackers that come too close, weakening them and even scaring them off.