The World Cup is not simply "winning a bunch of ODI games". Winning a World Cup means that you can call yourself the best one-day team in the world.
I would take a series victory in South Africa over a victory in the Champions Trophy, Asia Cup or any other one-day series for sure.
World Cup > Away Victory vs. Aus > Away Victory vs. Eng/SA/NZ/WI > Home Victory vs. AUS > Victory vs. PAK > Away ODI Victory vs. AUS > Away ODI Victory vs. SA >
All Other Test Victories > All Other ODI Victories IMO
By the way, by Victory I mean a positive series result, not a one-off.