Defenders were statistically better with the buffs, and generally better with damage when soloing.
Corruptors were better with damage on teams. Since team damage usually is focused upon AoEs, Corruptors end up doing more AoE damage.
If you wish to team and not blast much, Defenders are good. If you wish to solo and solo AVs, Defenders are good. If you wish to team and blast as a major action rather than as an afterthought, Corruptors are good.
MMs are a different game, leaving aside that their secondary selections were a bit limited.