Hmm, I'd probably just do a works count, since I don't have page counts for a lot of what I read (too many audiobooks). I definitely don't have word counts for the book-books I read so even if I wanted to get fancy and look up paper equivalents for my audiobooks I'd just convert words > pages at some standard approximation (250-300 wds/page?).

I do leave kudos on everything I finish, though I also re-read a lot and it's only one kudos per fic. So I don't know if that would work as a metric. I definitely don't read or finish everything I open... :/

I'm not shy of a decent amount of data post-processing; when I look at my goodreads reading data I usually manipulate and supplement that info a decent amount. So I could weed out fics by hand that I don't think I read.