dufferama,
there's a never-ending debate as to whether the best league in Europe is in England, Spain, Italy, Germany etc. It depends on how you like your football, IMO. I love watching premiership (England) matches because they are generally high quality, attacking matches. I also like Spain's Primera League, for the same reasons, whereas Italy's Serie A is a little slower, slightly more defense minded.
World football stars tend to go where the money is, who will pay the best wages etc (from my cynical point of view). A few years back there were only a few foreign players in England, but since the introduction of Sky's money we've seen an influx of them. Similarly you'll see a whole host of foreign players in all the major European leagues. Big teams like Real Madrid, Barcelona, Bayern Munich, Juventus, the Milan clubs, Man U , now Chelsea (thanks to Abramovic's money) etc etc all have top drawer foreigners in their ranks. Funnily enough, the Chamions League final this year was contested by two teams from supposedly 'weaker' leagues, France (Monaco) and Portugal (Porto). Perhaps the worm is turning and in a few years we'll see the majority of French players playing in France, Dutch in Holland, etc. Then we could have a proper debate as to what domestic league has the best domestic players.
One other thing though, the English Premiership will be a damn site stronger next season now that Crystal Palace are in it!