I have been a long-time user and supporter of Simplenote for iOS, a straightforward note taking utility that provides cloud syncing and, via Notational Velocity, the ability to sync and use those notes on a Mac. Simplenote came at a time Dropbox did not have an API, and the built-in Notes.app for iOS was lacking in a number of important ways.
The Simplenote-NV workflow suffices if those are the only two applications you want accessing your notes, but it failed for me in some ways that have a lot more to do with how I use the notes than anything the apps themselves may be lacking.
I set up Notational to save my (synced) notes to Dropbox, both for backup and to allow me to access them anywhere. When Dropbox opened their API to developers, the number of text apps that provided integration with the service increased significantly, so I was also able to link my
Dropbox/Notes folder to these other apps. But any edits made in one place wouldn’t show up in the other until my Mac had a chance to sync the two, which was a form of friction in need of elimination. I know Simplenote added Dropbox integration for paid accounts, but with that I realized that I no longer needed Simplenote for being a frictionless cloud sync note app; I needed a great text editor for text files in my Dropbox — both short form (notes) and longer pieces (blog posts).
For now I settled on PlainText for general-purpose writing and note-taking, and Textastic for code and Markdown (incidentally, I find Textastic to be the best Markdown editor that I have tried, even though it is not specifically geared to that task.) They both work great with Dropbox and fit my workflow much better, and they both allow navigation of one’s entire Dropbox, if set up as such. (I also use iA Writer for some kinds of longer text, though it syncs with a different folder in my Dropbox.)
In closing, I should point out that Simplenote has been a great companion for a long time (from before the app was free) and it fits many other workflows perfectly. But, in seeking a good balance, I’ve come to realize Dropbox-based sync is both superior and sufficient for me, and maybe it is for you as well.