Best
1 France - Adidas - bright blue, very recognizable
2 Netherlands - Asics (with blue shorts)
3 classic Aussie/Italy/New Zealand/China/Ethiopia/ Etc. color styles
4 USA (10.000m men, the 100m final kit, red and blue)
5 Jamaica (especially women as they look like classic Ottey)
Worst
1 UK (only New Zealand should wear black)
2 Kenya (needs to have red/green/black)
3 Spain (red and yellow make orange)
4 USA the blue ones and the 'striped shorts'.