Hard call. But probably Shippuden.
Old Naruto failed us in a way. It was all about getting us to know the ninja world, system, and a decent background on events to follow. But sadly Kishi has retconned this series many times through it's life time.
Hashirama and Madara should have been hinted at, at an earlier point. The other villages should have been visited. More missions for team seven and the Sound Five should have lived.
For the purpose it should have had, I give it a B+. It was fine, but for what we have now... We were in no way prepared.
Shippuden, however is suppose to carry the plot. Take it to new places, and work with the world that was expanded upon and reveal SOME. But really, it shouldn't have shown us more about the world than the Original Series had. Action is great, we love it. Don't even lie. And really, up until the start of the war things looked great.
My complaint is that the main character has gotten all the spot light in an entire war. Naruto should have LISTENED to Itachi and conserved his chakra. I would have prefered it if other characters got the chance to have their own epic battles and show how much they've grown. It would have fleshed everyone out more.
And interesting ninja that aren't from Konoha need that. Not just the Konoha 11. Edo's were also made a joke of unless you were essential to the plot. They shouldn't have been hit or sealed so easily.
A strong few edo's vs a few ninja we were recently shown/some we have know would been an epic battle! We would have seen a large new arsenal from both sides and everyone would be like "Epic!". Which is why I enjoy the Darui vs Ginkaku Kinkaku fight so much.
Shippuden would get a low A from me. For what's worth, Shippuden is better for me... It revealed more than the original had and the battles were generally more fun to watch. Only a select few battles can I say I would enjoy going back to see in The Original Series.
Kimimaro vs Gaara/Lee
Lee vs Gaara
Zabuza vs Team Seven (Both times)
Orochimaru vs Hiruzen
Sound Four vs Sasuke retrieval team
Naruto vs Sasuke.
And there were a hell of a lot more fights too, the Forest of Death fights. Chuunin Exam fights, Stage 3 fights, Gaara vs Naruto, etc.
So. . I went off on a tangent. But yeah, I think Shippuen is better.