I've always used a lot Evernote before, Google Keep later, but I've always felt that both of them were missing something I needed.
- Evernote is very complete but too complex generally speaking, offline notes are available only on paid version and "too many clicks" are required to accomplish a task.
- Google Keep is perfect to me for its interface but on the other side it has a poor multimedia attachment support, needs a registered account (like Evernote), and has only manual notes sorting.
So, starting from this point I started developing from scratch an open source application that is still far from being complete but is growing thanks to actual beta stage users feedback.
If somebody would try it it's on Play Store or give a look to the Google+ Comunity to check beta versions!
You can directly find the app source code here: https://github.com/federicoiosue/Omni-Notes