Ronaldo for me based on players i have seen play live . For those i have not seen, it must be Duncan Edwards and George Best who were out of this planet when on the pitch. May they both rest in peace.
Cantona, followed by Keane, followed by Robson. Best three United players I ever clapped eyes on. For those I never personally saw play, Edwards, Charlton, Byrne, Best.
For impact he had on the club it is Cantona. He was the difference that took us from a good team to a great team. It was no coincedence that in 95 when he was banned we lost the title to Blackburn and I don't think it was a coincedence that when he retired in 97, the season after we lost the title to Arsenal. At the time I thought we would never win the league without Cantona! It's funny I had the same attitude opposition fans have for us when we lose a key player, I thought we would fall apart but I have learnt that this is a special club who continues to make superstar after superstar. Cantona was the first of this era. We had heroes during the 'barren years' such as Whiteside, Macari, Robson and Coppell but none of them were a true superstar like Cantona. Though Robson was one hell of a player. Keane deserves a mention as well. What a player. Never gave the ball away, no prisoners in the tackle and he couldn't half finish well.