I use Snapseed on Android. It's a practical app with many photo editing tools
I like how I can edit my photos here,
Priime - Edit photos with the styles of the world's top photographers. Smart suggestions, fast editing, and inspiring collections.
VSCO - VSCO® is an art and technology company empowering people everywhere to create, discover, and connect. CompanyVSCO® is a trendsetting art and technology company that .
Nizo - A better iPhone camera for shooting film
PicsArt - Explore 100,000,000+ awesome images and photos on the web
VSCO Cam - VSCO Cam is an iPhone, iPod Touch, & Android camera app w/ elegant, minimal processing options.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.