Kyle. followed by Kilowog.

I'd say Kyle followed closely by Hal

Guy Garder. I love his jerky attitude.

Guy Gardner
 
Then Kyle, Hal, Kilowog, and John.

@methos: no sorry the original ion was created through marty jordan the son of hal jordan well technically he was the part of parallax hal that accepted earths sins and the universes mistakes he first appeared when kilowog waa bought back to life as a dark lantern who tried to find hal jordan but learned he died by sacrificing himself but then the will power ring made marty jordan out of hals positive side and with kyle they convinced kilowog to stop by showing him the new lantern corp which he rebuilt soon later marty merged with kyle becoming ion while hal jordan was spectre at the time