I use Line Camera app to edit photos by adding text and combine multiple photos into one photo (collage).
I also use Instagram app to change the appearance of colors and lighting of the photo. This app is also used to share photos with friends on Instagram, Twitter, Facebook, Tumblr and Flickr.
The sharing of photos can also be done in Path app that is connected to Facebook, Twitter, Foursquare, Tumblr and WordPress. Path also has the ability to edit the colors and lighting in the photo.
Other photo sharing apps are Twitter, EyeEm, Pages from Facebook, and Google Plus.
I rarely edit my photos using the Photos app in my iPhone. I only use it when I want to share my photos from Twitter app only.