Coppertop

Still haven't seen episode 3, but here's a thought:

Showing the movies in order (1-6) would make the end of the series much more powerful. You start with Anakin as a child, and see him slowly develop into Vader as he falls to the dark side. He tries to bring his son over with him, but Luke proves too strong to fall to the temptation. The moment when Vader sacrifices his own life to destroy the Emperor and save his son from death or worse (Vader's own fate) becomes a much more powerful moment. If you've only seen 4-6 you've only seen Vader as the Sith Lord that he is, with little or no good qualities. His redemption at the end of Jedi doesn't carry too much weight. But having seen him first as the innocent boy who turned into a Sith and ultimately saves the day makes the entire series his story - thus his sacrifice is more meaningful. He catss off the dark side and returns to the light.

Yeah, you lose some drama regarding the fact that Vader is Luke's father, but taken as a whole the series is all about Vader. The other characters take a backseat to the drama that is the life of Anakin/Vader.

edit - Just thought of this. Isn't Vader the only character to appear in all 6 films? I haven't seen 3 yet, so I cannot be sure.This would definitely point to him as being the most central character in the series.

I guess Obi-Wan also makes an appearance in all the movies (even though in Jedi only as a spirit). But I still think this holds true to the entire story being all about Vader as Obi-Wan was his mentor and ultimately died by his hand.

edit edit - The droids were also in all the films.