I've heard it's a tie between the first Superman story from ACTION #1 and The first Batman story from DETECTIVE #27.
After those, I wonder who is next?
Best reprint of a complete single comic book as close to original as possible - The USPS "Action Comics" #1 REPRINT From 1998 with the FIRST DAY ISSUE stamp on a special overlay cancled in Cleveland,OH on September 20th of that year.
If you've never seen it - it's really neat - actualy Golden Age size,better quality paper than the original newsprint. ALOT better than the oversized reprint! It's one of my favorite pieces in my collection. It cost $7.95 when it came out.