Based on the Champions League, the rankings would be this order in accordance to the number of teams left in the Quarterfinals:
Primera Liga (3) -- Barcelona, Deportiva la Coruna, Real Madrid
Bundesliga (2) -- Bayer Leverkusen, Bayern Munich
English Premier League (2) -- Liverpool, Manchester United
Greece (1) -- Panathinaikos
According to the CNN/SI Top 10 World Clubs Poll:
England (3) -- #4 Manchester United, #5 Liverpool, #6 Arsenal
Germany (2) -- #2 Bayer Leverkusen, #7 Bayern Munich
Italy (2) -- #3 Inter Milan, #9 AS Roma
Spain (2) -- #1 Real Madrid, #8 Deportiva la Coruna
Argentina (1) -- #10 River Plate
