What are the five strongest reducing and oxidizing agents?
Are we playing top trumps?
The most potent oxidant is undoubtedly the fluorine molecule. Dioxygen gas, is a less potent oxidant than fluorine, but still very fierce. Anyway, your question is quantifiable. And we could consult tables of standard electrode potentials, and come up with fluorine (which is screamingly hot),
The strong reducing agents include the alkali metals, naturally, and the alkaline earth metals. Anyway you can read the order on the Table. There is a lot of research directed by industry towards the development of new materials for batteries. Why should this be? (If you can't answer immediately, then check your mobile). Clearly, we could not use a lot of the potent reducing agents such as the alkali metals (why not?). The ease of recharging the cell (i.e. how it reversibly responds to current drain and recharge) is also a highly important practical consideration.
Are you happy with this?