I'm in the middle of a redesign of our church's devotional app. (I'm not going to link to it because the design is hideous.) So I've spending time researching typography and layouts for mobile reading experiences. Recently, I came across NeuBible and it has been the most enjoyable of all the Bible reading experiences I've found on mobile devices. Here's some of the reasons I believe it's a superior experience to the other offerings currently offered:
Typography - You only have four choices of fonts in NueBible. They've chosen Breve, Graphik, Sentinel, and Texta. I don't know if they could have made a better choice in font selection. While my current selection is Texta, I'm delighted that they've included Sentinel, which is one of my favorite typefaces to arrive in the last 10 years.
User Interface - One knock on this app could be it's lack of features (reading plans, share sheet, etc.). However, it's one of things that I love about this app. By removing those features, it allows the reader to focus on the text.
The only thing I would add to this app would be the ability to turn off the numbering of verses so that the text flowed in the same manner as the ESV Reader's Bible.
Now in fairness to other apps, there is a fee to download versions such as the NIV, ESV and NASB. So that is a bit of drawback if you're looking for something that is completely free. Though it does offer the HCSB for free in side the the app.