What version of each Alien movie should i watch?

I recently bought the Alien Anthology Blu-ray and Prometheus. I plan on watching them all before Alien: Covenant comes out. But each movie has some sort of directors cut and i was wondering which version of each movie i should watch? I know already that i should watch the theatrical for Alien and the DC for Aliens but i'm not sure about the other two and as far as i'm aware Prometheus has no special edition.