First a warning. This post is spoiler free, but it does touch on topics that may be in the first 3 chapters. I would appreciate it if those who have read these chapters do not make comments that spoil the readers of this post.

This will probably be a rather lengthy post of my speculations. Feel free to rip it apart.

I got done with my re-read too soon. I have been spending too much time asking myself questions like:

Which character (other then Rand) has hurt the shadow the most?

If we are going to be subjective about it, it is imperative to come up with a criterion for which events hurt the shadow the hardest. After some thought, I broke it up into different categories, from hard hit to glancing blow:

Hard hits directly to the DO
1. Cleansing of Saidin
2. Bowl of the Winds
3. Rand destroying army of darkness in Tarwin's Gap (ushering in spring.)

Moderately hard hit (Capturing or Destroying one of the Forsaken
1. Balthamel destroyed
2. Aginor destroyed
3. Be'lal destroyed
4. Ishmael destroyed
5. Asmodean Captured
6. Moghedien Captured
7. Lanfear destroyed
8. Rhavin destroyed
9. Samael destroyed
10. A'ran'gar destroyed (I hope I have the right gar)
11. Semirhage captured
12. (Future?) Tower is reunited and chaos that divisions in the WT has been healed. This has not happened yet and does not necessarily concern the Forsaken but in my opinion it is important enough to bump it to the next level.
13. (Future?) Taim's faction defeated and routed (if it occurs in future).

Small hit but still felt (major plot of shadow foiled)
1. Battle over Falme
2. First battle in Tear
3. Rand rescued at Dumai's wells
4. Halima revealed and forced to flee
5. Seanchen converted from menace to ally with shadow (in future.)
6. Anyone who saves Rand from shadow
7. (Future?) Maseema's reign of chaos is finally broken

Glancing blow
1. Breaking the Shaido
2. Forming rebel AS army
3. Forming Legion of Dragon
4. Forming Band of the Red Hand
5. Controlling Andor and building up its armies
6. Great Escape of seafolk
7. Getting rebel AS to march against WT
8. Forming a large army or disrupting a DF or BA plot or exposing or killing BA or DF Ashaman.

With all of that grunt work out of the way. Here are the major candidates.

Perrin
Saved Rand at Dumai's wells and Broke the Shaido. Slowly building an impressive army for the light. Defeating the shadow spawn in the two rivers was impressive but I doubt the shadow cared that much.

Mat
Blew the horn of valere to delay the Seanchen enough that they could come into play for the side of light and not just cause chaos. Played an important but still incidental role in securing the bowl of the winds. Saved Tuon from Semirhage by kidnapping her. Started the great escape of the seafolk. Started the band of the red hand. Rescued the wondergirls. He also won more then a few battles, but none of them really hurt the shadow that much. There are certain events foretold for Mat that show his importance later like sacrificing half the light of the world to save the world. One would also hope that his battle skills will be used for a battle that hurts the shadow more, but for now...

Nynaeve
She was involved in TWO of 3 great events that directly hit the shadow. She was a major player in the Bowl of the Winds and a smaller player in the cleansing of Saidin. Further she captured Moghedien and was a major player in destroying Rahvin. Further she was a major player in foiling Semirhage's plan against the Seanchen and in capturing Semirhage. She has captured a BA as well. No other character besides Moiraine and Rand has hurt the forsaken so badly.

Moiraine
Destroyed Bel'al and Lanfear. Saved Rand's life numerous times. Set everything in motion.

Elayne
Major player in the bowl of the winds. (She is perhaps the most important since she set it in motion.) Participated in the capture of Moggy (through her a'dam). Build's up the single largest nations armies and brings it against the DO. (Dyelin or any of the others were too meek to do it.)

Egwene
Held the rebel AS together and not at each others throats despite what Halima was doing. Kept the rebels focused on WT. Help organized the rebel army. If she succeeds in organizing the WT and making it stronger then ever against the shadow then she will move up to making a hard blow. But for now...

Cadsuane
Saved Rand's life. Works to keep Rand sane. Important role in the cleansing, keeping Rand alive, etc. Helped save the Seanchen from Semirhage by helping to capture her. (Perhaps her and her ter'angreal were the most important part since without them Semirhage might have succeeded in surprising them.

Elza
Destroyed one of the gars.

Damer Flynn
Saved Rand and was involved in the cleansing

Romanda
Revealed Halima to be a forsaken.

Itulralde
Struck a major blow against the Seanchen slowing them down until they can be brought into the side of the light.

The BA hunters
If they succeed that is.

I still don't know if there is one main person after Rand, but after this I am leaning more toward Nynaeve then before.

RabidWombat