This Brexit commentary was my own material, and got 21 shares.
My five Facebook posts that got the most comments, in ascending order, were this Brexit commentary (actually copied from an FT journalist's tweet, with attribution):
...which was beaten by this Brexit commentary:
...which was beaten by this very brief Brexit commentary:
...which was beaten by this crowdsourcing question, which led to a blog post and then my Five Books interview:
...but all were beaten by this slightly stalkerish meme riffing off the Conservative Party leadership contest.
My five most liked (etc) Facebook posts of the year were in general less political. In fifth place, sheer vanity:
Beaten by this, where I should have credited the artist:
Beaten by this scene of debauchery from the work Christmas party:
Beaten by B's birthday:
But coming in at a massive 640 likes is a picture of me and an adult relative who is not a Facebook user; it is therefore a private post, but even so 640 people liked it. If we are Facebook friends, you can see it here.
However I should say that my most-liked Facebook post of 2018 was made after I had worked out the numbers for last year; it was our Christmas day picture with the whole family.