I dunno if I can vote on my own thread, but eh, nobody else is voting so why not.
It seems as though Arthur has many more abilities and ways to kill Arturia than vise versa. However, hax isn't the only factor here, as if it was, EMIYA would've stomped Arturia in their vs battle over on the main wiki. Strength and especially skill counts in this battle as well.
As for strength, at base it should obviously go to Arthur, since he's constantly High 7-A whereas Arturia's only 7-A. But, Arturia actually has a chance to one shot Arthur with Excalibur, as at full power it's unquanifiably above base High 7-A, which Arthur seems to scale to.
As for skill, you're gonna have to clarify me on this @GKS77, but Arthur doesn't seem to possess as much skill as Arturia does. Just some examples of Arturia's skill are displayed when she battled Hercules and Sasaki Kojiro.
Even though Hercules was more powerful than Arturia in every way, even though he was induced with madness, she still was able to beat him through sheer skill alone, even when being at a severe disadvantage throughout the whole fight.
In the fight with Sasaki, it was actually the opposite case. She was stronger in every way except for skill. Keep in mind that Sasaki's skill alone was basically able to make the world go "screw it, do whatever you want", and bend space to create three sword strikes at once. And guess how Arturia won. Not with her strength, but with her intellect, instincts, and skill (also luck, which she has a high amount of. It's literally a stat she has).
This also isn't taking into consideration her abilities, such as an instinct that borders on precognition, similar atomization abilities as Arthur has with her Excalibur, and of course Avalon.
Now that I listed everything about Arturia, you might be thinking I'm rooting for her, but I'm actually not. There's still things unexplained, such as Arthur's intelligence. I didn't even delve into his abilities that much either, soo... who am I rooting for? Well, nobody. They both have ways to defeat the other. Arthur has a crap ton of abilities at his disposal, and Arturia has a crap ton of skill at her disposal.
TL;DR: Going inconclusive for now until I have more information about Arthur, such as his intelligence and willingness to use the abilities at his disposal. Also things like what would he do for his first attacks, etc.
