This thread just keeps going Can't believe people are still arguing about last gen.
It would have been interesting to see more devs push the Gamecube in the same way the X-box was utilised. It was just that bit harder to make games for and less financially feasible to put effort in. As a few others have said, Gamecube had capabilities the X-box did not have, but it was far easier for devs to utilise the X-box as it was essentially a PC.
It also had more developer support; just because more devs worked on X-box does not mean that they're correct when they say the X-box was the most powerful system. To be perfectly honest I can't call it between the two. Both consoles have games that just aren't possible on the other system in their current form. I don't see how anyone can claim one is more powerful than the other.