Seems like a false dichotomy.
Aside from life support in one's final days, most practical medical interventions for prolonging life also result in significant improvements in quality of life.
For example, healthy diet and exercise contribute to extended lifespan, but they also improve quality of life significantly during all stages of life.
I can assure you that you'd never ever hold that opinion if you were a healthcare worker. A big part of our job is to maintain alive people with a horrible quality of life who should be long dead, oftentimes without even being able to know if they'd in fact prefer dying...
A related concept is the quality-adjusted life year (QALY), which is used when weighing the cost/benefits of certain interventions.
[1]: https://en.wikipedia.org/wiki/Quality-adjusted_life_year
Health-wise yeah it’s great to be young :)
Healthy diet for example is not a singularly defined term and depending on specifics can be argued to lower quality of life even if they improve health.