Autodesk's Sketchbook comes to mind as being the only one that's close to being on par with desktop art apps. Problems is you're stuck making images that match the resolution of your phone - so unless you've got a 512x512 phone it's not going to be any good for it.
There's a stack of apps rigged for pixel art, so if you don't mind having limited tools & having to prod palettes every few minutes one of them could be of use.
IsoPix Pro & Pixel Marker Pro being the best two of that group.
TBH other art apps on Android are pretty gash. Between instability & general crapness there's only really 3 worth using at all.
You'll find "demos" of them all on Google play, so give them a poke & see what you think.