I prefer Argy’s over Ptera’s any day. They have more stamina, health, weight, and more melee damage. Even know that Argy’s lack in speed compared to the Pteranodon’s speed the Argy is better than the pteranodon 100%.
Getting a massive TLC update in March 2018. The saddle will act as a mobile smithy, Argentavis will be able to carry with Talons as well as with its beak, reduced carry weight on obsidian and a few other unannounced resources (similar to the mammoth and wood), and will also gain a Rapid HP Regen upon eating (likely from devouring corpses and not specifically food from inventory). Like so people can see!