I personally use 2.0, as I think that the physics are more faithful to 1.3's, and I find that sometimes less is more (for beta 3, the newest build is pretty cool though.) I don't care for 1.4.4 because its physics seem more jarring and unnatural (well to me at least), I think that Teascript isn't as powerful as Lua, plus the developer kind of butchered it for his version, and I REALLY can't stand the developer. He's unkind and rude to his fans, even when they ask for help. But if someone else enjoys 1.4.4, I'm glad that they can and I will respect their opinion.
Here's a cow, I don't know what else to put here