I'll have two list; List 1 - pure sword, List 2 - all blades. I would also like to state even I have certain people that I am on the fence about or people that could be swapped for someone above/below them. This is something I've thought about for quite a bit over the books.
List 1: Purely Swords
1) Lan - Raised from birth to not only weild his One Power wrought blade but to BE his blade. Lan wasn't playing with the toys of his peers, but weapons of all kind since he could walk. His passion and focus to live his war(even before Moiraine) was engraved in his soul. The ko'di is symbolic of not a state of being for him, but the way he lives his life. Visualize al'Lan Mandragoran and you achieve a nightmare for both men and Shadowspawn. His level of mastery is NOT in question. Simply put, his level of experience is unrivaled. Being a Blademaster is like being any other master. What kills a skunk is the publicity it gives itself.
2) Rand - Destined to make or Break the world. A very young man in fact. A 3,000 year old soul in truth. No mans Mountain is Heaver than Rands. By pure trial and error - some would even say madness - Rand al'Thor has had to mature faster that anyone in the history of the current cycle of the Wheel. Fear. Hope. Uncertanty. Potential. The humanity to fail. The Power to succede. His will to learn ALL that he's been exposed to by accident, ta'vereness or him simply out manouvering his opponents has been driven by something that the Pattern allows for even within Tel'ara'rhiod - Need. His greatest weakness his is mortality. And his greatest strength. Depending upon your perspective, madness comes with a price...
Enter Lews Therin Telemon. Most Powerfull of all Aes Sedai in an Age where all things seemed possible w/ the One Power. He was a man of Peace, even discovering the 'sport' of swordplay with one of his peers. No ones fool, the Dragon was reawakened within Rand, allowing spontanious knowledge of weaves - and quite possibly swordplay. With the taint poisoning Rand's mind long enough to be unsure of subconcious thoughts in times of need the Dragon Reborn is failable, but no easy meat.
3) Galad - Galant. Gifted. Gorgeous. What more could a knight want? Much less a woman? Galadedred Damodred is Lancelot incarnate. Pure of heart, mind and body. His charisma and intelligence combined with his athleticism is rarely paired. His casual manner in the way he carries himself - the way he walks, talks and conducts himself in most situations with the asurety of righteoussness - speaks volumes of his ability to prove he has the mental and physical dexterity to back himself up through education and knowledge - in books and the blade. HIs physical beauty is in life is a correlation to his ability to deal decisive death.
4) Gawyn- Poor Gawyn. . . Always shining just a bit less bright that his half brother Galad. Owing him his life. Lessons in sparring were no break, perhaps because of the former reason. The middle man in an ongoing battle between loving his half brother and natural sister, whom had a one sided disliking on Elayne's end, he developed an easy manner in dealing with both while accelling at his lessons along side them. Torn between loyalty to his House, his duty. And wanting to become his loves', Egwene's, warder. Being slapped down by the very Aes Sedai he was taught to respect in matters regarding his sister was only adding fuel to the fires within. Also torn by the split in the Tower, the death of his Queen Mother and the accused killer, his sisters love, Gawyn Trakand has been developing a sence of confusion, strife, torment and revenge. All the more pure because he has no control over the rage deep within. These emotions combined, all fed to the Flame inside the Void, are a very dangerous combination which have been manifesting into a drive to take back the things that have been slipping through his fingers. Once he made his decission to take control, no one would stand in his way. And so it continues to be.
5) Chosen/Forsaken/Shaidar Haran - The 5th and final spot is one of conjecture because we simply do(can?) not know. We know Be'lal, Sammael perhaps even Demandred are proficient in sword work, but to what degree? When fighting Rand only Be'lal was able fight him blade to blade. Rand being green as he was was due to lose( Be'lal>Rand>Turak). The other fights between Rand and the 13 were w/ the Power. Aes Sedai lived longer in the 2nd Age so who knows which of the 8 male Chosen/Forsaken knew swordplay before the Bore was opened, turned the game into war with blades of Power/alloys and to what degree they took that skill to? The world may never know, but I'm willing to say one of them deserves a spot in my top 5 swords.
Now, as for Shaidar Haran, the Hand of the Shadow, who knows what info the Dark One is available to tap into?? Obviously we've seen him handle Chosen/Forsaken w/ no problem and it wouldn'd be far off to say he/it can use the One and True Power both. But what if in Shaidar Haran's future we see one of the legendary Blademasters encounter him? If a channeler Blademaster encountered him he might feel overconfident, shielding him, and clash blades with him. Perhaps knowing who the nonchanneler Blademaster is he decides to just fight the person thinking to have fun? That's neither here nor there, but the possibility is there. I can't in all fairness NOT consider Shaidar Haran a serious threat.
List 2: All Blade Weilders
1)Mat - Matrim Cauthon will be the first(and probably only, heh) person to tell you he's no Lord. He's a man who grew up in the Two Rivers milking his Da's cows and other chores when he could be found to do them. His father - the best quarterstaff user in the Two Rivers - taught him the way of the weapon. After a critical amount of Healing he swiftly dispatched both Galad and Gawyn Simultaniously. At this point he's quite good with his weapon of choice; however, after entering and exiting the ter'angreal at Rhuidean he became the most deadly fighter in the world. With his natural ability to incorperate the additional 1,000 years of fighting assimilated into his mind as if he lived all that fighting first hand his experience is peerless. He also aquired an ashandarei, a quarterstaff with a blade at the end. In addition to being ta'veren, his luck is at such an uncanny level as to have been quoted by multiple people(in the story of course) as the Dark One's own luck. With his charming ease with which he carrys himself, the way he'll shirk off what would appear to be a serious matter and stand up for something trivial to anothers eye, Mat is the kind of danger you never saw coming.
I really wouldn't feel right not including perhaps Rhuarc or some Aiel badass, but yeah, Mat sits at the top in my mind of ultimate blade weilding mo-fo's.