Wikipedia pageviews could serve as a useful indicator that I expect is strongly correlated with website views.
E.g. see the following comparison of the pageviews of several EA-related Wikipedia pages in 2020. As it turns out, Peter Singer gets about 2x the number of views of Nick Bostrom, 2.5x of effective altruism, and 12x FHI or GiveWell.
"Is EA Growing? EA Growth Metrics for 2018" has some data on this, and I look forward to doing it again for 2019-2020
Giving What We Can for 1 January 2020 to 31 December 2020:
Effective Altruism Australia for 1 January 2020 to 31 December 2020:
I remember finding the data from ahrefs.com about EA sites interesting. You can get a 7-day free trial of it if you haven't tried it out. I can't remember if it had data on number of views, but it had data on what links rank high based on certain keywords or topics, such as "effective altruism", on search engines.
Keeping in mind that website traffic stats are not exact, here are the numbers I have from Animal Charity Evaluators for Jan 01 - Dec 31 2020.
Users: 160,508
Sessions: 214,433
Pageviews: 430,692
AI Safety Support only started mid last year so hard to get a clear picture
So 1405 Sessions and 2627 Page view second half of 2020.
I guess that this site will be the biggest by at least 10x.
By 'this site' do you mean the forum or all the other resources on effectivealtruism.org? In either case, if the 80,000 Hours site counts as an EA site then I highly doubt that! My guess is that the answer is going to depend on how wide the catchment is for 'EA site', but most construals are going to put 80K right out in front. Maybe GiveWell is up there, plus the GWWC site and The Life You Can Save. I also think that Nick Bostrom's personal site gets a surprising number of hits. I would guess the forum is middling to top around these sites? Very interested in being proved wrong about that!
Obviously all these sites have their own numbers, but I haven't seem them pooled together in some publicly available resource (nor am I sure that would be useful). I do know of some exact numbers but don't think it would be sensible to share them without permission. Unfortunately, in my experience it's also not totally straightforward to glean those stats from the outside, although search engine rankings etc are a good proxy.
From 80,000 Hours' 2019 annual review:
From January - December 2020, the Forum had 168,000 unique users. So 80K "wins" by an order of magnitude (and as FinM notes, there are other sites that may be bigger than the Forum; GiveWell had ~600,000 unique users in 2018).
fwiw I said hits, not unique users. I am not surprised that 80k has more uniques.
Sorry for misinterpreting "biggest" — I just failed at basic reading comprehension :-(
FWIW, the Forum had roughly 1.2 million hits, so 80K's count of unique users is still higher than that number, and I'd guess their hits are at least double that.
You can start by looking at the Alexa engagement ranking - lower rank is (superlinearly) better:
nickbostrom.com: 367k
effectivealtruism.org: 187k
givewell.org: 140k
80000hours.org: 122k
slatestarcodex.com: 91k
lesswrong.com: 46k
etc.
Whoa, Lesswrong beats SSC? That surprises me.
I'd expect Lesswrong and EA Forum to be quite high.
But it depends what metric you are thinking of. Forums have a lot of active content compared to the other sites that are not updated as often. Forums probably have lower Unique User numbers and higher Page Views compared to these other sites