RiF for me. I was a fan of old.reddit. Liked the simplicity and didn't have a need for all those flairs. And the filtering options I felt were the most extensive of the reddit apps and close to RES. I came to like stuff like Boost for a more prettier UI with showing banners of the subreddit and avatars and the viewing options were really nice. But, something about RiF feeling like a mobilized version of RES kept it in my rotation and never dropped out.