I'm not sure that this may be of some help, but the oxidation of ferrous iron to ferric iron occurs rapidly with air at a pH of 8.5. Therefore, I suspect that pH may also be a significant variable for oxidation with hypochlours ion. If this type of oxidation is similiar, then sodium hypochlorite woud be my choice because of the excess NaOH in the sodium hypochlorite. However, the reaction may be so quick that the selection of reagent would depend on other considerations such as cost, availabilty, safety, etc.

grrun