I know answer to your question cannot be unique or acceptable for all. But I want to share some links I get redirected most of the time while looking for solution to my problems.

 1. Official [documentation][1] is at beginning phase as Magento 2 but it is getting better everyday.
 2. Alan Storm is the best magento [blog][2] writer I have ever seen. 
 3. [Inchoo][3] is consistent at it's blog publishment.
 4. [Mageplaza][4] is good place to learn magento 2.
 5. [Mukesh Chapagain][5] is outstanding nepali blog writer.
 6. [Cuong PHP][6] is new youtube channel but excellent if it comes to magento 2 coding guide I have found till now.


I wil come back to add more good links when I encounter them. Thank You.


  [1]: http://devdocs.magento.com/guides/v2.0/
  [2]: https://alanstorm.com/category/magento-2/
  [3]: http://inchoo.net/magento-2/
  [4]: https://www.mageplaza.com/kb/magento-2-tutorial/
  [5]: http://blog.chapagain.com.np/
  [6]: https://www.youtube.com/channel/UCVlVTjx6M6PyPHjS6FN-PHg