I've been getting most of my photo editing done these days on iPad with Apple Photos, Pixelmator, and Snapseed. Camera+ just released version 2 for iPad and it is now firmly in the rotation for me. As the name implies, Camera+ gives you lots of control over the iPad camera but what I really like about the new version for iPad are the photo editing tools.
I've always been a fan of Camera+'s "Clarity" filter which, as "push one button to make it better" filters go, a lot better than most. I also like the way you can use the brushes (via finger or Apple Pencil) to apply localized changes.
One gripe with this app though is its lack of Apple Photos extension support. Maybe there's a good reason but the app doesn't tie into the native Photos app so you have to make a copy of a photo into the app and then manually save the edited copy back to Apple Photos. That part feels stone-age to me. That aside, I like the Camera+ for iPad update. (Website)(App Store)