...GameCube. Website VentureBeat crunched the NPD numbers and has turned up the following results:
• Based on the console's first 26 months of availability, the Wii is on its way to become the best-selling console of all time — a title currently held by the PS2. (The Wii has been outselling the PS2.)
• During the first 26 month period, the PS3 sold 6.79 million units in the U.S., compared to 6.75 million GameCubes during its first 26 months. While the GameCube finished a distant third last generation, the console was profitable for Nintendo.
There are more figures and data in the link below.