Use Different Camera Apps to Improve Photo Quality
The Nexus 5 has both the standard old Android gallery app, as well as the Google+ Photos app. Both offer a pretty wide selection when it comes to editing photos after the fact. For example, you can crop, rotate, and flip. You can reduce red-eye, and brighten faces. You can apply numerous filters to change to tone, contrast, exposure, and colors. You can adjust brightness and apply various different frames, as well as straighten and/or mirror images. It's a solid, if basic, set of tools.
Camera FV-5 doesn't have its own editing tools. Instead, it hooks into the Google+ Photos app for both storing images and editing.
ZOOM's editing functions, such as they are, are mostly the same effects that you can apply to photos before you take them. ZOOM has its own internal gallery for the images captured with the app, and when you select any single image it can be shared, edited, or trashed. If you press the editing tool, you'll see the same selection of effects that are already part of the actual camera app. As I mentioned above, these effects let users add frames, create composites, set crop, as well as create greeting cards. You can also perform more basic edits, such as flip horizontally or vertically, rotate, adjust levels, create collages, and so on. I like that there's a big "reset" button that will undo all the changes you may have made.
The social sharing tools encompass every possible avenue. If you have any app installed that can share files and/or photos, it shows up in the list when you want to send your photo somewhere or to someone.