I'm also not surprised that contests rank so high as they promote direct engagement and activity.
Very true, being forced to comment will certainly help the count!
As you give away some rather sizable rewards in your contests, I think a resteem is a fair trade for the chance to win.
It's mostly my 'sphere' commenting on these posts as unsurprisingly, gaining visibility is pretty tough these days. I was hoping today's 'top posts in tag' would reach more people as I think many tag-based communities would be interested in what's been popular/engaging.
I'll keep on though as usual, even more so while we are in a dip. Cheers!