Green Lantern Week: Why Were They Chosen?

While Hal Jordan and Alan Scott came from different backgrounds, they each had some common elements on why they were selected:

• They were courageous in their disposition, Hal mentioned as "fearless" while Alan merely "heroic".
• Hal was closer to the downed spacecraft of Abin Sur, the previous Green Lantern. Alan's power battery happened to be on his train... although a later story indicated he was bequeathed it by eastern monks.
• While Abin Sur had a lengthy career as the previous protector of sector 28415, Alan's predecessor was Mr. Billings an insane businessman revived by the lantern.
• Why he and other Lanterns were chosen was soon revealed when Hal was summoned to Oa by the Guardians of the Universe. Alan was kept in the dark for decades until the Starheart finally revealed its own origin tied to the Guardians.
• Hal was motivated by honoring a fallen hero, Alan was motivated by vengeance for the  criminals involved in slaying victims of the train he was riding.
• While Hal's costume was a standard issue uniform worn by all Green Lanterns, although each modified his own depending on his preferences and physical appearances, Alan's was completely of his own design.
• The Emerald Crusaders quickly lived up to they faith bestowed in them by those who selected them, swiftly acclimating to their abilities by their new found power rings.