Why would you even need an app for writing notes? The role of note app is not unambiguous as the same content could be saved in files and keep in cloud storage.
Unfortunately, Microsoft Word and Google Docs for example are too heavy especially when it comes to mobile usage. Personally, I use a note app to store ideas, observations, travel tickets and debts that should be quickly accessible. I might move some entities to document files when the content increases. That’s what happened whit my blog ideas.
Earlier I my choice was Evernote which is probably the best-known app for notes. There was no lack of functionalities but problems with synchronization together with decreased free plan made me to go for Google Keep. Google Keep simplistic features in line with the company ideology. The app has nice search and labeling features. In general, simplicity is a big plus but the editor doesn’t even have text editing options. On the other hand, you can attach pictures and voice recordings to notes. You can also set the type for individual notes to a task list or hand drawing.