FromTheShire: In an average deck I think I'm likely sticking with Sun Titan due to the ETB, slightly larger body and vigilance, and sheer inertia
Even in a 40 life format (*cough* Commander *cough*), Athreos tends to be a great long-game clock that also nets you good stuff here and there, at least in the early game
So, while not as much of a slam-dunk as Sword of the Animist, Bitterthorn is still very good, especially in builds that play Sword of the Animist for ramp rather than as an equipment in their suite
When you cast a spell, you get to add one red mana, which wont disappear as you move between steps and phases
For their sake, here are the details
For historical reasons and because there are more than the usual differences between printings, Alpha and Beta are often regarded as different sets