Evernote

I would recommend this app because you can make notes with images and audio message in them. You can download it for Android & iOS.

Springpad

I would recommend this app because you can attach products and places to notes. You can download it for Android & iOS.

Bamboo Paper

I would recommend this app because you use your fingers to write notes. You can download it for iPad.

Dropbox

RECOMMEND-You can share files between your computer and phone. You can download it for Android & iOS.