Lelouche, hands down. For reasons that already stated above and he hid his identity behind mask. No one knew his real identity, except for a very select few.
-> Lelouch's power could work once for every person. How many people in the world again?
-> Light could write names in the Death Note to kill them. Now this is something I've always wondered, could the Death Note ever run out of blank paper to write on? >3 Well, if they could, then Light is screwed when he run out of places to write names in his Death Note.
And if ever Lelouch and Light meet directly face to face? Lelouch could zap Light's will through eye contact in a split second before Light could find out his name, much less writing it down in his Death Note. x3