Ya know Ive read the short stories about Dunk the Lunk and Egg (of whom I take the odd pleasure of being a namesake) and I got to tell ya as GRRM would write it I dont think Brienne would be that easy a victory for the Sword of the Morning.
For those that dont know Brienne is somehow related to Ser Duncan the Tall, a famed commander of the Kingsguard who joined the knighthood through slightly scandalous means but he proved himself against the apex of chivalricdom (I think I made up a word there) in martial combat and managed to achieve victory through size, strength and quite frankly determination...all traits that Brienne has inherited. I honestly feel that as GRRM would write it Brienne would somehow prove the victor.....
That all being said I voted for Arthur Dayne...because thats how I would write it.......