Dear putu, sorry for the inconvenience but I am an App Developer for Android and recently read your comment about Google Keep not having an Undo Feature. Anyways, my App is also an Audio Note Taking App that I developed over the last 2 years.
I could never really directly compete with Google Keep because they are a giant corporation with lots of help and resources (and I worked by myself on my App).
My App does not use Syncing for backup (we use email). There is no automatic restore (user has to do it manually if they need to). We also don't take photo Notes. All Audio Notes are stored as plain simple text (which is good enough for our customers).
However, here are the advantages of my App "EZ Notes"
It's truly far easier to use than Google Keep. All nice buttons at the top with one Tap. More importantly, your Audio Notes pop-up instantly on the screen and not inside the editor at first. So you can be more mobile and on-the-go for work, exercise, shopping, school etc.
My App has lots of nice "cloud functions" for browsing, searching, shopping items and email / SMS. These are completely missing from Google Keep.
My App also has a very nice Painting Application missing from Google Keep. But everything else is very basic and simple. We also Archive your deleted Notes automatically and you can use our "EZ Undo" to quickly recover a Note.
My App is called "EZ Notes" and costs only $1.49 cents so I can make a living.
Feel free to check my profile page and our mission statement at the top of my g+ page. Then you can also look for my App "EZ Notes" by Alexander Madani.
By the way, my App is only about 3MB on your precious Android. Google Keep is over 11MB! Plus because I eliminated a ton of useless bloat (bells and whistles like Syncing, photo capture, animations etc...) my App stays very very small on your device in the long term. Much smaller than Google Keep or Evernote.
Hope you can support me and if you liked my effort, please kindly give me a nice feedback to help me.
Thanks my dear friend.
Developer of "EZ Notes"