>>49520915
Mamizou is also there, being of similar age or older. Moreover, Aya is a self-serving freelancer, essentially, while Mamizou is tanuki ring-leader. And yet, Aya is almost constantly a step ahead of that stinky raccoon in terms of folklore/youkai knowledge and in terms of what is happening in Gensokyo.
Both Yukari and Yuyuko struggle with recalling anything beyond 60 years in A Beautiful Flower Blooming Violet Every Sixty Years and that story stresses a lot that things considered by someone uninteresting have a life-span of at most 60 years in memories, which is tied to internal cycle in Gensokyo. The fact that Aya knows so much trivia about various things, which can be seen in LE but also in DS, means that either she constantly learns about things, or that she finds even those seemingly obscure things interesting enough to remember about them. In any case, I would say it's a testament to her curiosity, a quality very useful for reporter.
Also rude, thousand years and some isn't ancient for a youkai, Aya is still in her prime.
All in all, the important thing to take away from this is that Aya is the best.