Anyone in GoT fandom probably has more of an opinion on this topic than me, but what stood out to me about this article
was that people find it hard to navigate FFN.
"Fans’ creations over the last eight years represent a massive amount of content. Currently, there are 927 GoT stories on FanFiction.net and 31,284 on fan fiction site Archive of Our Own."
I found that disparity suspicious. It turns out they were right about AO3, at least probably around the time they wrote the article. The link goes to the tag page rather than the works page
where apparently 312 stories have been added in the last two days.
Yet at FFN, the number is actually ~7,900
not under 1000. It didn't surprise me that there would be more works on AO3. For starters, eight years ago I wrote a meta piece about features of large fandoms
in which I compared works at both sites. These results fall in line with what I found then.
My guess is that AO3 has more GoT works for several reasons. The first is that it probably had as many A Song of Ice and Fire
fans before GoT even came along, so they were more likely to post there once GoT launched. The oldest ASoIaF work on FFN is from January 2007, 8 years after its launch whereas the oldest one on AO3 is from November 2009, mere weeks after the site went into open beta. But I suspect due to the tagging system at AO3 the number there has become hopelessly muddled with show fans. FFN now hosts ~8,800 stories for ASoIaF, its most recent posted this February. The oldest GoT fic was an outlier from 2009 but others began to join it soon after the show premiered in 2011.
The second is that it's the sort of show that, despite being very popular, probably appealed more to older fans than younger ones. While I'd bet that AO3's userbase has begun to look much more like FFN's, it didn't start out that way. GoT fandom is now at least 8 years old, meaning that it started around the time I wrote that meta piece.
The third is that I suspect FFN use has declined while AO3's has risen. I don't have any data that confirms that, but it would be my guess. FFN continues to be larger and, unless it purges another significant batch of content, will keep that title for a while still. AO3 will hit 5 million works this year, while FFN had over 6 many years ago. It no longer shows the total number of works on the site, however its 20 most popular fandoms account for 2.8 million on their own as of a few months ago, so it's safe to say it's added several million more by now.
It also used to have higher SEO than AO3, but I notice that's also changed. A recent search on the term "fanfiction" (slightly different results on fan fiction, but essentially the same) has FFN as the first link, the Wikipedia page second, followed by AO3, Wattpad, the Urban Dictionary definition, the Medium piece I linked to yesterday that involved the Commaful recommendation (suspiciously high ranking, I think), the Fanlore page, a FFN apps page, the Reddit community, and an eBooks guide to fanfic sites.
This last one was supposedly updated last year but still lists Quotev, Kindle Worlds
(closed, in case anyone still didn't know), and Wattpad first, and then gives stats for AO3 that would have only been current in 2013. But at least it includes Asianfanfics, as well as Deviant Art, Ficwad, the Internet Library(really?), Feedbooks (?), Good Reads, Tumblr, LJ, FictionPad, and MediaMiner. Other top results are a variety of explainers and app links, as well as a comedy piece on YouTube. Sadly the best explainer is 2 pages in.