Yeah it all depends on lead platform, and after that who did the porting and with what budget. Multi-platform development wasn't as straightforward as it is now with identikit Intel/AMD western focused consoles (or even last gen's PPC pipeline).
Splinter Cell was a typical example for western games, it was made with PC and Xbox as the lead platforms by the game's actual developer Ubisoft Montreal. This was cut down significantly in a port to PS2 by a B team in China, and that version was then ported to Gamecube with a few enhancements. Gamecube basically got a higher performance version of the PS2 version, when it could have actually handled something much closer to the original.
Most Japanese devs had PS2 as lead platform, so both GCN (and Xbox if it for a port) were higher performing versions of those. In the rare cases GCN was the lead platform (Sonic Heroes, or games originally planned as exclusive like Viewtiful Joe, Killer 7 and RE4) it varied from clear best version (Sonic) to dominating (RE4).
All three had some things the others couldn't do, and some PS2 games would have had real trouble being ported, which may be one reason (separate from exclusivity deals) why most of the PS2's highest graphical quality/performance games (eg MGS3, Jak games) didn't get ported, so points of comparison are hazy.