Surely on cultural impact Harry Potter has to win. While GoT had a decade flash in the pan, Harry Potter is still deeply in the cultural zeitgeist. "Muggles", "You're a Hufflepuff", etc have become cemented into our vocabulary.
GoT is undoubtedly more complex, interesting world, but it never had a generation of children reading the midnight book release. That the author actually penned the series finale is also worth something.
The Hugo voting is kind of skewed since it’s a membership thing where anyone can join but one has to be aware of it and care enough to join.
That's what I was thinking! I was sure my parent meant GoT.
But there can't be many metrics at all where GoT beats out HP for the title of "biggest fantasy series of our time".