I use Snapseed on Android. It's a practical app with many photo editing tools
I like how I can edit my photos here,
Trigraphy - Photo editing app that allows you to make mosaic/abstract looking art.
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 .
Dreamscope - Make and share 'deep dream' images using dozens of supplied styles or your own.
PicsArt - Explore 100,000,000+ awesome images and photos on the web
Photomosh - Turn anything into a vaporwave
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.