I'll break the rules, choose Final Crisis, and pick The Flash Family. Final Crisis is amazing but it ushered in the end of the thing in DC I liked most.
Actually sticking to the comic at hand, I would probably pick Donna Troy's origin. I really, really like Donna and wish she got her due more. 90% of her mess is due to having to change her because they wanted to reboot Wonder Woman after COIE. Very few characters have suffered more for ancillary things than Donna has.