If we're talking pure tech, then it's gotta be xbox.

No there wasn't, the Xbox absolutely murdered the GCN along with every console of the gen. In fact, the Xbox was the primary reason a lot of us weren't all that impressed graphically when the 360 was unveiled.

The GCN was fantastic bang for the buck though, and could do some gorgeous graphics all things considered.

Xbox was more powerful. CPU wise, they had parity, while the Pentium III on the Xbox was clocked higher, IPC on Gamecube's processor was higher and architectural differences made it have better real world performance, therefore the lower clockspeed didn't mattered. GPU wise, Xbox was more powerful, even though GC actually had the game that most pushed polygon counts on that gen(20 million for Rogue Squadron 3). Since Xbox GPU supported pixel shader and vertex shader, though, games generally looked better on Xbox thanks to that, even though it was the main reason that made the GPU underperform on the polygon count department since pixel and vertex shader operations took a lot of the GPU's processing power.

On paper Xbox, But as far as which console had the best looking game of the gen it goes to GC. Rogue Leader was heads and shoulders above anything Xbox or PS2 had.

I'm guessing that none of you have played Ninja Gaiden (2004). Even when NG Black was released a year and a half later, it was still the best looking console game I'd ever played.

PS3 only made it look better a year and a half later with Sigma.

Xbox was somewhat more powerful, however, in all blunt honesty, games like Star Wars: Rogue Squadron, Metroid Prime, Pikmin, RE4, and Twilight Princess especially all looked just as good if not better than the best looking Xbox games.

It's a damn shame that Factor 5 went under then, eh? Nintendo really should have bought them back in the day.

Absolutely. They were magicians with tech. 

The Game Cube was a rather powerful machine - very close to the Xbox. Surprisingly close, however, it messed up on a few key memory issues. So they Xbox and GC didn't get to blow the PS2 out of the water so to speak graphic wise.

I think some of that power was overlooked because it was considered the 'console for kids' but they way it was marketed, the way it looked, and Nintendo's reputation.

Even the Wii is only like a few times more powerful Game Cube, or something like that. Showing you how powerful the GC really was.