Hi, thanks for getting in touch.
In response to your questions, the leagues that are generally considered to be the best in terms of the talent playing in them, as well as the quality of football played within them are the so-called 'Big Three' of Europe - that is the English Premier League, the Italian Serie A and the Spanish La Liga. The German Bundesliga follows closely behind these three, but is not considered prestigious enough to attract the major world stars to their clubs.
The main reasons behind these three leagues being considered the best in the world isn't really down to nationalism per se, rather a number of contributing factors which have built these leagues up to the standards they currently enjoy.
The English league is the oldest league competition in the world, having been formed in 1888, which means that is often thought of as the standard bearer for competition. Its long history has given world football a number of famous clubs such as Arsenal (based in the Islington district of London), Liverpool and of course Manchester United, who are possibly the most famous club in world football today. The English league is also highly regarded to be one of the most passionate in the world in terms of fan support (although the English game suffered greatly from hooliganism in the late-'70's through to the 1980's, the problem of hooliganism has largely been eradicated from the game), and the standard of the stadia within the league is second to none, mainly thanks to the Hillsborough disaster of 1989 (in which 96 people were tragically killed, forcing a review of how stadiums were built).
Spain's La Liga is enjoying a renaissance at the moment. It wasn't really considered to be amongst the best in the world until the mid-1990's when Real Madrid started to become dominant in European football (with Champions League wins in 1997, 1998, 2000 and 2002). The biggest clubs within La Liga are Real Madrid, Barcelona, Atletico Madrid, Valencia and Deportivo de La Coruna, although it is only Real Madrid and Barcelona who have made any major impact on the world game.
The Italian Serie A was considered for many years to be THE pinnacle of club football, with many major clubs such as Associazione Calcio Milano (or AC Milan as they are more commonly known), Internazionale (of Milan), Juventus (of Turin) and the two Roma clubs AS Roma and SS Lazio being amongst the giants of the game. A massive injection of money into these clubs in the 1980's reinforced their dominance of the European club scene with Italian clubs often featuring in European Cup and UEFA Cup Finals.
The one common factor within these three leagues is money, with most of the major club football transfers being between these leagues. For example, the current world transfer record is £49.5million (around $60m) for the French captain Zinedine Zidane, who signed for Real Madrid of Spain from Juventus of Italy. It is highly unlikely that any club outside of England, Spain or Italy will ever be able to break that record by signing someone for more money.
As well as the German league, several other European leagues are also considered to be quite prestigious, but are nowhere near the standard of the 'Big Three'. Holland's KPN-Telecompetition features Ajax Amsterdam, Philips SV Eindhoven and Feyenoord Rotterdam, all of whom have won the European Cup in their history. France features Olympique Marseille, Paris St-Germain and AS Monaco, all considered 'big' clubs in the European scene. Scotland, whilst currently in decline, have the two Glasgow clubs - Glasgow Celtic and Glasgow Rangers.
Outside Europe, the only leagues that are considered to be 'major' are those of Argentina and Brazil. Although the United States and Japan are trying to compete with their leagues, neither have the historical fan base yet to be able to compete with the more established leagues. America's MLS (Major League Soccer) was only formed in 1996, with Japan's J-League being formed three years earlier.
As for a 'World Series' for football clubs, the top competition for international clubs is generally agreed to be the European Champions League, which is open to the Champions of all 42 European leagues, the runners-up of 20 of the leagues from countries with larger populations, and sometimes the third-placed and even fourth-placed clubs from the biggest leagues such as Spain, England, Italy and Germany, although this system is currently under review from UEFA, the European governing body. The winners of the Champions League are crowned Champions of Europe.
The South American equivalent is the CONMEBOL trophy which, like the Champions League, is played for by the Champions of the South American countries, as well as a number of runners-up. The winners of this competition are crowned the Champions of South America.
Each year from 1960 until 2000, with the exception of 1977 and 1980, a one-off match was played between the Champions of Europe and the Champions of South America to crown the 'World Club Champions'. This was changed in the year 2000 when FIFA launched the FIFA World Club Championship, a 'World Cup' for club teams.
The World Club Championship is played for between the Champions of Europe, South America, North America, Asia, Africa and Oceania, as well as two teams from the host country to make it an eight-team tournament. The first tournament was played in Brazil, and was won by Corinthians of Brazil. The tournament is likely to be played every two years from 2003 (the 2002 tournament was delayed due to the World Cup). The original 'World Club Championship', played for between the European and South American champions is still played for, with a new name - the Intercontinental Cup but is no longer as prestigious as it once was. Although the FIFA World Club Championship is the first truly 'World Club Championship', the European Champions League is still considered to be the best competition simply because of the standard of competition within the tournament (ie, the World Club Championship is likely to be won only by European or South American clubs for the first few years because the standard of the other continents is relatively poor).
As for your last question, it is likely that a big club team such as Real Madrid or Manchester United could defeat a national team such as Brazil or Germany. Even more so when you consider that the club team's players are together for around 40 weeks of the year, and the national teams are together for only around 8 weeks of the year. Club teams playing National teams is rare, although Sunderland of the English Premier League did actually play the Republic of Ireland in May of this year, Ireland winning 3-0.
If you have any more queries about the game in general, please feel free to contact me at paul@sunderland1973.freeserve.co.uk and I will be happy to help.
If you are interested in finding out more about the history of the game, I would recommend finding a copy of the following books :
The Guinness Book of World Soccer; Guy Oliver; Guinness, 1992. **** (would have been a five-star recommendation, but it loses points for it only being printed in 1992 and having no follow-up editions).
Soccer : The World Game; Desmond Morris; Oxford, 1995 *** (ideal if you want to learn more about the history of the teams in terms of their following)
Rothman's Football Yearbook; Jack Rollin; Headline, 2002 (a new edition printed each year; concentrates mainly on the leagues of England, Scotland, Wales and the Irish leagues, but does have comprehensive sections on world leagues.) ****
European Football Yearbook; Jack Rollin; Headline, 2002 (like the Rothman's edition, but features more prominently on the European leagues. HIGHLY recommended) *****
I hope I was of some help to you.