1. Moridin - Post-breaking he ran the Trolloc Wars and toppled Hawkwing's Empire, he is also presumably responsible for acquiring all the male Aiel channelers and construcitng the Black Ajah. Plus his gambits on Rand at the end there were pretty inspired.
2. Demandred - Took over Shara and showed up with a hoard of channelers plus the one thing the shadow didn't have, a significant gateway-capable ground force knowingly willing to fight for the shadow. Plus recruited Taim, and combined with his allaince with Messana (White Tower) and Semihirage (Seanchan) nearly gave the shadow control of every group of channelers except the windfinders.
3. Graendal - Knocking out Arad Doman, brain-raping the great captains, plus her general defense of Shayol Ghul was pretty big.
4. Taim - Though I think Sanderson wrote him poorly, Taim succeeded in training and turning a lot of channelers to the shadow, slightly overshadowed by turned Aiel and Demandred's Sharan acquisition.
5. Messana - Master-minded the lion's share of the chaos in the white tower.
6. Semihirage - Toppled the Seanchan empire after getting it to dance to her tune, then basically driving Rand insane. Loses points in my eyes because her plan to seize Rand was frankly dumb enough a lot of us thought it was designed to fail IIRC.
7. Sammael - Conquered a major kingdom and almost killed Rand if not for the help of Moridin.
8. Rahvin - Same as Sammael but didn't last as long and was killed by Rand, thoughalso liek Sammael with the help of another (albeit unwilling) Forsaken.
9. Belal - Like Sammael and rahvin, but lasted even less time and got himself balefired.
10. Aginor - His principal accomplishment seems to be making the Shadowspawn, a pretty big deal but way out of date and all the forsaken apparently had major AoL accomplishments for Team Evil, Lanfear helped open the Bore in the first place for instance. After his EotW showdown with Rand he just tagged along with Rand until he had to run for cover then got himself nuked at Shadar Logoth.
11. Lanfear - Although ultimately almost seizing victory for the shadow via Perrin, Lanfear's principally screwed her own side over repeatedly.
12. Balthamel - Killed by a tree, resurrected to give Egwene headaches and some black ajah nightmares, balefired so hard odds are anything else she accomplished that I forgot got wiped out anyway.
13. Moghedien - Sort of like Asmodean, she mostly probably helped the light more than hurt it training Nyneave, Elayne, and Egwene.
14. Asmodean - Kind of a no brainer, he achieved nothing positive for the shadow except maybe by accident.

So, the good guys - and you can skip down my nomination process to the list if you like. The whole Emond's Field exodus crowd should be on the list - Rand, Mat, Perrin, Egwene, Nyneave, Lan, Thom, and Moraine. Which is eight. That leaves us six others, and in roughly chronoligical order of appearance for the nominees: Min, Loial, Logain, Elayne, Gawyn, Galad, Bryne, Agelmar, Ingtar, Hurin, Siuan, Verin, Birgitte, Faile, Aviendha, Rhuarc, Bashere, Narishma, Olver, Cadsuane, Tuon, Ituralade. I'm sure I skipped some good ones there, but 21 for six slots remaining seems sufficient.

I'm going to go ahead and scratch Agelmar, Ingtar, Hurin, Narishma, and Ituralade right away. Ingtar has a big black mark, Hurin and Narishma didn't really do too much, and Agelmar and Rodel are great captains who just got less screen time then Bashere or Bryne. Galad's main accomplishment of getting the whitecloaks to serve as a net positive for the Light is debatable since they had already started working for the Seanchan who showed up anyway. Gawyn was arguably more irritating then Egwene and his great accomplishment is freeing Siaun and later saving Egwene, meaning he'd rate lower than either of them anyway, so gone. Olver's acocmplishment is being shoehorned in as the horn sounder, I loathe Faile, and Tuon borders on evil, plus I don't think grudgingly bringing your army along to fight the Forces of Darkness really deserves a clap on the back.

So that cuts us down to Min, Loial, Logain, Elayne, Bryne, Siuan, Verin, Birgitte, Aviendha, Rhuarc, Bashere, and Cadsuane. Bryne was an interesting character but mostly secondary to Siuan, and while she did spend twenty years of her life with Moraine and Lan trying to set the stage for Rand, at the end of the day with Nyneave, Moraine, and Egwene already on the list and Verin and Cadsuane on the nominees, I think her Aes Sedai accomplishments have to be considered insufficient to make it. Ditto off with Logain, most of the good black tower stuff he did was off screen, he got owned by Demandred and outmatched by Taim. Also while Birgitte is a major hero, it was mostly past life and if we're counting that we'd have to toss on Hawkwing and a bunch of others. I hate to cut him but Rhuarc. Even though he and Amys were most responsible for helping Rand get contorl of the Aiel, and he was steadfast, he never did that much. My last cut, even though she's the only one of Rand's gals I actually like, has to be Min, most of her heroism is a pale shadow of Thom or some of the other badass-normals, her help with the grand plan is a continuation of Herid Fel's, so she wouldn't deserve to be on the list for that unless he was, she helped Rand stay sane but then was also the tool Semihirage used to snap his mind, and that leaves here foretellings, which I think are debatable as to whether or not they actually helped anyone.

So, my 14:
1. Rand - duh
2. Lan - One man killing machine in the blight and everywhere else for decades without any special powers except the warder bond, helped find, protect, and train Rand, and finished it off by killing Demandred.
3. Mat - Beyond being the greatest general for the light, busting into both the Stone and Finnland to rescue Channelers, and just being generally cool Mat killed Couladin, the Gholam, and Fain when he was all Dark God mode, 3 of the half-dozen or so non-forsaken main villains of the series.
4. Nyneave - Beat Moghedien on multiple occasions, attacked Rahvin, healed stilling, healed Taint-madness, helped cleanse the Taint, and was part of the trio that went to the Pit of Doom.
5. Moraine - Also part of the trio that went into the pit of doom, and like Lan spent years fighting the Shadow and then helping to find, protect, and train Rand. Killed one Forsaken for keeps and took out Lanfear.
6. Perrin - Killed Lanfear too, along with Isam, was the +1 to the trio that went into the Pit, instrumental in both the battle for the White and Black Tower. Saved Rand from the Shaido/Elaida/Galina, later kicked the Shaido around some more. Demoted in coolness for his bad taste in women and general angst.
7. Verin - Probably gets the most credit for taking down the black ajah and blunting their efforts, in all probability off screen did as much as Moraine and Siuan in protecting the TR-crew, knowingly committed suicide for the light, and general coolness.
8. Cadsuane - Multiple centuries of badass-ness, helped capture and break Semihirage, helped keep Rand sane, coordinated the battle at Shadar Logoth against multiple forsaken, and was one of the main coordinators of the battle in the Blasted Lands.
9. Egwene - Accomplished a lot but much of the credit goes to others. Never really did anything particularly useful until she fended off the Seanchan attack, but lobotomized Messana, killed Taim, and helped wipe out most of the Black Ajah. Probably deserves to be higher on the list but she's damned irritating.
10. Elayne - Along with Nyneave and Mat, recovered the Bowl of Winds, killed and defeated several black ajah, and stabilized Andor by holding Camelyn until the Trollocs utterly overran the place. Commanded the forces of the light, minus the Seanchan and pre-Mat, though this appears mostly honorary.
11. Thom - Also apparently killed some black ajah, along with Elayne's father and Moraine's brother, and the King of Cairhien, plus some High Lords. Protected and trained Rand and Mat, then later Elayne and Nyneave, helped rescue Moraine from the Tower of Ghenjei, then guarded her, Rand, and Nyneave's back during the sealing of the bore.
12. Loial - Would be higher but his big final grand success, recruiting the Ogier to fight in the Last Battle, apparently was unnecessary as they were coming anyway. Played as big a role in rescuing the horn as Hurin, led the heroes through the waygates multiple times, helped Perrin protect the two rivers then save Rand at Dumai Wells. The goes off screen with Manfor to run around closing waygates and preusmably helping to get the Ogier on the warpath. Shows up with the other Ogier for the last battle.
13.Bashere - Fought the shadow for decades and at least one of the great Captains should be on here. Bashere was the first to lend his troops and skills to Rand, helped orchestrate his campaigns in Illian, against the Seanchan, and in Arad Doman before running a pretty successful fight in Andor in the Last Battle.
14. Aviendha - Along with Nyneave, Mat, and Elayne managed to recover the Bowl of Winds, fought Graendal and for that matter Rhuarc.


So that's my 14 for both teams, in order of ranking