Alright. I'll give my vote to August, but I'll do what I can in the subsequent posts to present some interesting scenarios, interpreting both characters in the best possible light.
Before that, I have a hypothesis regarding the trend of the arguments, and that is IF both characters are underestimated in a similar manner, THEN Irene is more likely to come out on top mainly because of the default dragon advantage that remains no matter how both of them are downplayed, but IF both characters are overestimated in a similar manner, THEN there are more chances for August to come out on top mainly because of his copying ability and magical heritage, both of which stand to benefit the most in favorable optimized interpretations.
Basically then my position is premised on a very generous view of their powers, with August's ability trumping Irene's in the long run. But that only serves to answer the question as to who has the superior magic ability, and not yet the question as to who would win in a match-up. I shall try to deal with that in the next posts.
As for the claim about Irene being the only one to be able to stand up to August, it can be interpreted in different ways to favor one or the other, but suffice it to say that it puts both of them above everyone else, and in that sense they are on par in having no peer except each other, and with only the likes of Zeref and Acnologia surpassing them.