1. Ruud Van Nistlerooy
Mike Egerton/EMPICS SportThe Dutch striker was really in his element at United and produced numerous great displays over the 5 years that he was there, plundering a hatful of goals - 150 in 219 appearances to be exact, which is a phenomenal scoring rate, especially after he suffered what would normally be classed as a career ending injury. However, after falling out with sir Alex Ferguson due to poor form and his criticisms over fledgling superstar Ronaldo, he left in 2006 for Real Madrid. Sadly for the player, he never really recaptured the heights that he hit at Man United with his other clubs. At Madrid he was in and out of the team and his scoring rate gradually declined and he missed out on being in the Netherlands squad on a regular basis. Eventually he wound his career down with comparative minnows Hamburg and Malaga, and Van Nistelrooy himself admitted his behaviour had been unacceptable in his latter years at United, even ringing Ferguson to apologise, a tale he recounted in his autobiography. And frankly Van Nistlerooy is right to have regrets - if he had stayed at United, he could have become the all-time top goal scorer. Which other players do you think should probably regret leaving Manchester United? Share your thoughts below in the comments thread.