What is the difference in resolution and quality between SCART, VGA, and HDMI?
First: The maximum resolution of your TV is important. Your TV have probably a resolution of 1920 * 1080 Pixel (FullHD).


  A (Mini) Display Port can display about 3840×2400 Pixel
  
  VGA is an older standard, an was created for an Analog connection
  between devices.
  HDMI was created for a Digital connection.


So, the HDMI option is the best, because HDMI fully supports FullHD resolution. 

VGA could probably be display FullHD or HD Ready (1280x720 Pixel), but it's not recommended.

So, the best decision is to buy an Mini Display Port - to - HDMI Adapter.

It is hard to give a detailed information of the cababilities of each Video-Output, because there are many differnt version of each one out there.