Managarmr is still the bast traveling mount, IF you call crawling on the ground and suffer through constant harassment traveling. You used to be able to dash across the map, if you mutate and level up it's stamina enough, but now you can only dash once and you are forced to get back to the ground.
I didn't even bother to tame a mana in my latest difficulty 10 storyline playthrough, just bring my rock drake over to extinction and call it a day.
I'm gonna give Wildcard credit though. At least they remember to also nerf the wild managarmr. Not like the wild giganotosaurus. They didn't nerf them because they have the role of screwing with player throughout the whole game.