DVD or Blu-ray?
If you have a DVD player then you are restricted to DVD but if you have a Blu-ray player you can play both.
At just 720x480 and only one third of a megapixel, DVD image quality is very low and audio is compressed. In comparison, Blu-ray is full HD 1920x1080, has four times the pixels of DVD and audio is uncompressed. It's win, win.
Blu-ray costs more because the media is more expensive and even on our fast computers, writing a feature length movie takes almost four hours per disk.