[devit]

What's wrong with search?

If you want, say, a calendar app, search for "calendar" both in the App/Play Store and on Google or Bing (along with "android" or "ios").

You'll usually find a bunch of link to apps, plus several webpages reviewing several of them.

Once you find the names of some popular apps, you can also put all their names on a web search and find more webpages comparing them.

It works just like searching for anything else.