For my money it is
this rendition by Marvin at the 1984 NBA All-Star game. Up until this point it was simply unacceptable to sing the national anthem any way other than straight forward.
To me, this is the epitome of the national anthem as it represents America as a melting pot. It is incredibly beautiful in a musical sense; and it shows us that it is okay for everyone to inject themselves and their culture into Americana. I know Jimi did it first; but I think Marvin did it better.
At the same time, as beautiful as it is, I almost wish he had never done it. This opened the door for people (who do not have one twentieth the talent) of Marvin to freely butcher the anthem in the name of artistic license.