Quality or Quantity When it Comes to Life??

In sociology class last night, my professor was talking about whether quality or quantity was more important in life. I think for life itself, quality is much more important. For instance... my mother's patient has been dealing with ALS for about a decade... they just pulled the plug on her now when she couldn't blink, speak, or move in any way shape or form for about 8 years now. Her quality of life sucked and she is better off now. Timmy on the other hand could still have a quality life... hopefully... he's been in acoma for a month today... and the longer hes out the more likely it is that he wont be waking up. In the case of a 21 year old... is 21 yeaars enough quantity to have true quality? The question is yours.