The main features of the reddit app I used (joey) that I enjoyed:

• More condensed/streamlined interface with less wasted space compared to the official app. Also much faster and more resource efficient with imperceptibly short loading times for text posts.

• Ability to set custom filters to automatically hide posts with a given keyword in the title or subreddit name from my feeds.

• Way better built in image/video viewer compared to the official app.

• Option to move the title bar to the bottom

• Subscribed subreddits shown as tabs in the title bar with the ability to swipe left and right to switch between them.

The feature I miss the most: anytime you opened a post or followed a subreddit link, you could swipe right to instantly go back to where you were like the back button in a browser. So if I clicked on the subreddit name from a post on the frontpage to open r/aww, opened a post in r/aww, and clicked on a link in the comments to open r/illegallysmolcats, I could then swipe right and be back where I was in the comments, swipe right again and be back where I was in r/aww, then swipe right again and be back where I was in the frontpage. And this stacked indefinitely so you could be 15+ subreddit links deep and still go back to where you started in a few swipes.