I really like The Good Book Company. Brad Byrd is a friend and is always telling me about new resources they are putting out. But before he could even tell me about it, I noticed the Explore app on The Good Book blog and downloaded it on my phone. It's excellent.
It's a self-paced devotional that you can use daily or use as you want. You start with 28 daily devotions free as an introduction to the devotional, and then you can subscribe to more. And these aren't just written by some no-name dude behind the scenes. They come from guys like Tim Chester, Christopher Ash, and Tim Keller.
Go to your app store and find Explore and give it a try. I think you'll like it.