Maybe compare a list of major exploits?
Major accomplishments off the top of my head, and by no means a complete list:
- Prevented a war with the Romulans (Balance of Terror)
- Stopped the twin Lazarus's from destroying two universes (The Alternative Factor)
- Stopped a potential invasion from another Galaxy (By Any Other Name)
- Stopped the Planet Killer from passing through a densely populated section of the galaxy (The Doomsday Machine)
- Destroyed the "space amoeba" before it could reproduce and endanger many worlds (The Immunity Syndrome)
- Stopped the utter annihilation of Earth's surface (ST:TMP)
- Stopped all non-oceanic life on Earth from being annihilated (ST:TVH)
- Prevented the assassination of the Federation President and likely war with the Klingons (ST:TUC)
I'm not an expert on the other shows. Who wants to chime in with lists for each of the other Captains?