In both the browser extension and mobile apps of the Phantom wallet, you can view the current list of top and trending apps (labeled as 'Sites' on iOS) by visiting Phantom's Explore section. To get here, first select the 🌐 icon along the bottom of your wallet view and then clicking on Apps ('Sites' on iOS).
Here you can find many things, one of which is the Top and Trending section that's found within the Apps/sites tab.
The Top and Trending lists are part of the drop-down menu which contains a list of the top 10 apps that Phantom users are connecting to and/or making transactions through. For your convenience, you can click on any of these apps to be sent directly to the app/site that you're interested in.
Filtering made easy: Top/Trending and by Network
There are also two ways to filter the list that you are looking at. By clicking on either of the drop down menus you may filter by Top or Trending and by network.