I'm not sure how the ratings are achieved. If it's downloads per day (week, month, etc), Comixology may have hit near saturation, whereas PowFolio started recently from zero.
If you are talking about why people don't rate Comixology higher, too many people hate the changes made when Amazon purchased them (me included).
Register for free to join our community of investors and share your ideas. You will also get access to streaming quotes, interactive charts, trades, portfolio, live options flow and more tools.