I'm starting to quite like Keep. Two reasons - being able to set a reminder by location; "when my phone is here, remind me this". Second, and so simple - saving a note automatically when I close the app. So many others don't do that!
Yea, damn rare for an app to not save on the fly, as it's how the data structures work by default on Android (and it addresses the memory management issue as you describe)
I can think of one app I have that requires you to save, out of the ~250 user apps on my phone. And I chose that app for that feature (a text editor).