iOS: Longform is one of the best sites online for reading in-depth articles. A recent update to the iOS app makes it easy to follow writers and publishers.
With the Longform app you can still browse staff picks and popular stories from around the web, but you can also now follow specific authors and sites, which makes it feel more like an RSS reader. You can also bookmark articles to read later, recommend articles to friends, and sync everything between the iPhone and iPad.
Longform (Free) [iTunes App Store]