Sir Matt Busby
Sir Alex Ferguson
Sir Bobby Charlton
Ryan Giggs
George Best
Denis Law
Duncan Edwards
Eric Cantona
Bryan Robson
Paul Scholes
Wayne Rooney
Roy Keane
Gary Neville
Peter Schmeichel
Denis Irwin
Rio Ferdinand
C. Ronaldo
Thats probably it and probably in that order for me.
There is a case for many others. Notable mentions include; Violett, Foulkes, Rowley, Beckham, Carrick, RVN, Van Der Sar, Evra, Solskjaer, Vidic, Bruce, Pallister, Hughes.