Top notch performance for all six years (summer 1939 to summer 1945) that constituted the European portion of WWII. Probably the only two fighter aircraft which can make that claim. Many of the competition mentioned (P-51D and Fw-190D come to mind) were available only during the final year, 1/6th of the total war period.
Which is also why the Bf 109 served so many of the top scoring 'experten' so well.
They were both outstanding designs and both sides would have been in big trouble had they not had theirs whilst the other side had theirs. The initial advantage over their contemporaries that both had, and which all aircraft designers strove for throughout the war, was speed. You can have all the other attributes of a good fighter aircraft, many mentioned already, but slow is no good. Otherwise something like a CR.42 would have been the best fighter of the early years of the war
Speed combined with good tactics allows you to fight on your terms.
Cheers
Steve