Pro HDR X

The world's most popular HDR app, now on iOS 8

Reviews
Discussion
I swore by Pro HDR for the longest time to improve my captures before processing and uploading them to Instagram. After iOS 8 came out and I upgraded to my iPhone 6 Plus, HDR Pro no longer worked reliably and the UI hadn't been updated, so I all but abandoned the app. Just today I realized that they actually released a new version rewritten for iOS 8. $2 well spent, IMO.
I absolutely love this app and use it a ton.