Thought this would be a fun thread. SOME SPOILERS FOR THE BLADE ITSELF TO RED COUNTRY. Obviously this is mostly speculation but let's have some fun. Let's make a rule to exclude everyone with magic abilities as any normal person would not stand a chance against Bayaz or similar supernatural characters like Fenris the Feared or the guy in Best Served Cold. Let's think of them as a 1v1 duel kind of scenario.

5 Caul Shivers - A mighty lumbering warrior whose strength is seen again and again. He has survived countless encounters and is more than capable of besting almost anyone in a fair contest. He is last on this list as I can't quite recall him fighting through near impossible odds and seemed to be close to evenly matched against Friendly. Still an imposing character who has stacked up a big body count.

4 Ferro Maljinn - Incredible with a bow and has even been able to shoot birds from the sky. Has been able to escape numerous traps where she was out numbered or disadvantaged. Smart, cunning and very adaptable in combat.

3 Whirrun of Bligh - I recall in The Heroes he speculates that he has killed around 30 soldiers. Often is fighting without armour with a massive sword. He has potentially invented the sandwich. Outstanding survivor.

2 Bremer Dan Gorst - Without a doubt the best warrior in the Union. Survives an encounter against Eaters. Charges into the most dangerous spots of the battlefield and fights against some of the best the North has to offer including Glama Golden (who has won countless fist fights to the death) and looked good against Whirrun.

1 The Bloody Nine - The man with no comparable, whether he is fighting a horde of monstrous creatures, outnumbered against warriors, fighting magical entities, once he is blood-lusted there is seemingly no human that can match his terrible power.