Personally , I would chose the nexus 5. The advantages of the nexus 5 are that it has a faster processor, a better quality screen (higher resolution and better viewing angles), is smaller and lighter,and the camera has optical image stabilization (when filming the camera won't shake as much and makes video seem much more professional) and last but not least you will always (for at least the next 2 years) get updates to the latest version of android. The advantages of the galaxy note 2 is that the screen is larger, the camera generally takes better photos (slightly) and the battery life is slightly better.
It is up to you, but ultimately if you do not require the larger screen of the galaxy note 2 , then the nexus 5 is a no-brainier.