My Arsenal blog is considered controversial by 95% of the readers and I receive a lot of comments -considering my traffic. So I second that controversy works. I have had posts with over a hundred comments on quite a few occasions and I would say I average about 30 comments per article.
I'm not in the habit of commenting on blogs as I once did. I now try to save my best ideas for the digital point I was thinking also that sometimes posts of a very technical nature (such as tutorials) have a tendency to get a lot of "thank you" type comments and requests for clarification. It seems to me that people are also more likely to comment when it appears as if your blog already gets a lot of comments. The herd mentality. Also, you have to make sure your readers get to the end of your posts. If I can't make it through a long-winded story even about a topic I'm interested in, then I won't be able to comment.
Back when I was writing more often the best stuff I wrote began as a coment but eventually wound up on an entries on one of my weblogs. Comments are a good oblique strategy for getting the brain going some days. Richard