That's a great question Xeno!!! There are 3 books that I remember reading the heck out of, and still have the tattered originals from 1974, late 3rd grade. Dead of Night #4 from 6/74, Astonishing Tales #24 from 6/74, and then the one i loved the most, and could have sworn was my first comic book I bought was, Werewolf by Night #20, but it's from 8/74, so my 8 1/2 year old memory must be off a bit, lol.
I do know for a fact, that the first Hulk, which became my favorite character to collect, was #181 which my dad got at a U-Totem store for me. That one lost it's value stamp.....somehow