The biggest by far was my Brexit post on 31 January, which I had been brewing for three and a half years.
The second biggest was my full Hugo details post, which I was able to get done a bit more promptly thanks to being a deputy administrator this year.
Only two posts got more than five comments, my review of Titus Groan with eight:
and my review of a fascinating paper on Tolkien (which has been withdrawn from publication, unfortunately):
Some day in 2021 I will have to put in place an alternative blogging platform.