Recs.
Updated
The fast, open, and privacy-respecting replacement for Windows and macOS. elementary OS is a Linux-based operating system that is completely open source and deeply respects your privacy. It comes with AppCenter, the open, pay-what-you-want app store for indie developers.
SpecsUpdate
Pros
Pro Sane defaults, simplicity, limited configuration
Sane defaults with less confusion for new users.
Pro Consistent development practices
All elementary apps are written in Vala and hosted on GitHub, and there are standard APIs such as Contractor for applications to interact with one another. This is different from most distros, in which apps are written in a variety of languages. This design decision makes it easy to get started developing for elementary OS and to understand how the various pieces fit together.
Pro Large ecosystem of first and third party apps developed specifically for the distro
Pro With new tweak tools customisation is not a problem
Now the OS is amazingly customisable.
Pro It is based on Ubuntu
This means the wide variety of repositories and Debian's available are easily usable in Elementary OS. It is built on Ubuntu LTS with all its qualities and support.
Cons
Con Defaults to Nouveau drivers, which can cause graphical issues
Rather than giving the option of non-free drivers.
Con Old base and applications
The slow release schedule makes the applications outdated. It drags behind Ubuntu LTS (on which it's based) which itself drags behind Ubuntu which is often still quite far behind Arch for example.
Con Very slow development cycle
Elementary does not offer any release date for their stable releases going more with an "it's done when it's done" attitude. Making depending on newer apps a difficulty as well as a poor choice for those that need consistent release schedules for their OS.