My First concert was the Beatles, in Luxembourg, in 1964...before they became such a hit in the States. Perhaps the Best concert I went to was Pink Floyd, doing their Dark Side of the Moon album at the Chiefs Stadium in Kansas City, several years ago.
First concert for me was Elton John in the mid 70's at the height of his "costume" phase. Best concert I went to was also the Dark Side of the Moon concert. Outstanding.