Of the ones I have read...

1) Superman from Action Comics #1


1974. The Famous First Edition reprint.

2) Batman from Detective Comics #27


1974. The Famous First Edition reprint.

3) Spider-Man from Amazing Fantasy #15

4) Fantastic Four #1

12) Thor from Journey Into Mystery #83


1976. Stan Lee's "Origins of Marvel Comics" book.

6) Green Lantern/Green Arrow #76


1992. The Green Lantern-Green Arrow Collection, Volume 1, first printing.

8) Avengers #4

10) Avengers #16



1999. The Essential Avengers Volume 1.


11) X-Men #1


1976. Son of Origins of Marvel Comics.