Auron. Auto life alone with same stats as Basch still gives him win. If sphere grid is finished than it's a stomp.
Auron just simply has better abilities. I guess it also depends what weapon they use as well. I mean you could say Deathbringer and hopefully kills Auron both times with extreme luck, or give him Zodiac Spear whereas you can give Auron's Masamune beats any weapon in FF XII.
__________________ It was not impossible to build Rapture at the bottom of the ocean. It was impossible to build it anywhere else.
I am going to assume Auron and Basch are even in terms of Strength, speed, endurance, and agility according respective to their games. Just because Auron can do 99999 damage in FFX does not equal an auto win for him because its damage RELATIVE to your battle system. When comparing universes 1 point of damage from one universe does not equal 1 point of damage from another universe.
I am going to give the edge in swordsmanship to Auron because he only uses one weapon while Basch's weaponry skills are diluted among many.
I am going to give the edge in stamina to Basch since Auron does need to rest every now and then.
Auron has the willpower advantage since his willpower prevented him from being sent, so he beats Basch in the willpower department. I haven't seen Basch use his willpower to overcome a spectacular feet in FFXII.
Auron's intimidation factor does not affect Basch's game since he is mentally trained well enough to handle intimidating opponents.
What really wins this match up for Auron besides for the swordmanship, and willpower advantages is his composure to remain calm and collected. Even though Auron might be injured and losing, his composure will give Basch the appearance that he still has a lot of fight left. This will cause Basch to always be a little defensive while fighting Auron because Basch will not be able to tell when he is weak, thus preventing Basch from rushing and moving in for an all out attack.
On the other hand, Basch is more likely to show signs of weakness and fatigue compared to Auron thus alerting Auron when to rush in to finish off Basch.