who would you say is the top dog of all of them
You ask the fandom, it'll be Arthur Dayne/Jaime Lannister/Barristan Selmy/Daemon Blackfyre/Aemon the Dragonknight.
Commonality? They're all sword wielders and swords get +++ points in fantasy lore.
In reality?
Robert Baratheon. He was viciously skilled with all types of weapons(during the rebellion, King Aerys made Jon Connington his Hand because he had a very martial reputation. Robert, wounded after losing the only battle he ever lost in his life was hiding in a brothel when Jon Connington surrounded the town he was in with an army. Robert came out of the brothel with a sword in hand and beat Jon Connington half to death, after killing Myles Mooton, a famous knight and five others. He did that while wounded, and with his secondary weapon.)
Outside of Barristan Selmy, nobody has a kill list like Robert Baratheon.
He's famously associated with his hammer, and the nature of battle means a swordsman has to attack key spots if someone is heavily armored but a warhammer?
They just need one good hit and bones are broken and organs pulped.
He's 6⁶, probably close to three hundred and just a legendary warrior.
Plus, the tragedy of Robert Baratheon requires him to be the literal best warrior ever, to make his downfall that much more profound.
Jaime/Daemon/whoever except maybe Dayne(cuz his sword is magic) I'd put all my money on prime Robert Baratheon.