When comparing Outlinely vs Notational Velocity, the Slant community recommends Notational Velocity for most people. In the question“What are the best OS X tools for writing and finding plain-text notes?” Notational Velocity is ranked 2nd while Outlinely is ranked 5th. The most important reason people chose Notational Velocity is:
The interface is clean and unobtrusive.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Writer Friendly
Focus mode, similar to writing app such as Byword.
Pro Organization Features
Drag, drop. Indent, outdent. Hoisting.
Pro Tagging
Great tags and filtering support. Tag Autocompletion.
Pro Library
All your outlines in one place, neatly organized. Search for any document instantly.
Pro Simple and minimalistic
The interface is clean and unobtrusive.
Pro Free
Pro Syncs with SimpleNotes or Dropbox
Cons
Con Paid software
Con Feels a bit outdated
The last release was from 2011. Although due to its brilliant simplicity in doing what it's designed for, some might think there hasn't been any need for an update, as long as it still works with the newer OSs.