It's a stalemate / undecided.
Although, LCO probably comes in first place for turning their 2 NA fiefs into 21, they survived against VE when it was at it's strongest, and probably made more money through trade than anybody else (I could be wrong, FCC made a shit ton from trading as well).
FCC of course comes in second place, but it's a very close second. They have more people in their strategus faction than anybody else, won more sieges, and initiated a huge portion of the battles in NA.
But then there's the REALM OF THE GOBBLIN KING, who surpasses the ranking entirely. Daruvian started that shit as a joke and turned it into one of the largest factions in NA.
EDIT:
forget that ranking entirely, cup clan won strat.