Charts are where you find out who is actually winning a category, and both stores make them just annoying enough to check daily that nobody does.
Applyra now captures them every day: top free, top paid and top grossing, by category and by country, on the App Store and Google Play. Each entry carries its movement since the day before, so a chart run that takes an app from 84 to 31 is something you see rather than something you had to be watching to catch.
The dashboard version sits next to your tracked apps, so a competitor's chart run and your own keyword movement are on the same screen. The public version is free and needs no account.