The worst is Wii. Even though it had tons of 3rd party games barely any were good. The Wii U has amazing 3rd party titles with barely any terrible. N64 didn't have that much but most of the games were great. GameCube had actually a lot of 3rd party games and a majority are good. So here's my ranking best to worst
1. GameCube
2. N64
3. Wii U
4. Wii