I would believe that generally having a longer life is better because it allows you to experience more things and also allows you to be there for other people longer, such as children and grandchildren. The only reason it wouldn't be better is if you were in pain all the time.
Yes, I think that having a longer life is better than a short one. As long as you always have people around you and things to do, it shouldn't matter how old you are. Life can be fun no matter what. The more of it, the better. My grandmother is 83 years old and is still leading an amazing life!
Having a longer life indicates that the state of health one is in is good and that it is maintained well within the person's lifetime, even as they grow older. Having a longer life without any handicaps or disabilities enables one to experience the changes of the world, and I for one am looking forward to a long, healthy, and prosperous life that is full of curiosity.
If you think that longevity and peacefulness of life is the most important thing in your life, then it may be. However, I think "better life" means better quality of life for yourself. I believe no one can judge one's quality of life, but if you think you did best to reach the ideal quality of life, then you could say that your life was good. Also, one can make a great impact to many people even they had a short life (or maybe because theirs were short).
Yes, I do agree that longer life is better if and only if you are a healthy person and are having a good times with your family. That is because, I truly believe that quality is much more important than quantity. If your life is not so much of what you portrayed that it would be, I am sure that you are praying that you will 'go' faster. At the age of 70+, probably you will having some illness. As for me, I will pray that I will not be a burden to others around me.
I do not know what you meant by "Is a longer life better?" it would of helped to add something at the end like "Is a longer lifer better then a short life healthy life/ a fun life or having a sandwich?" because if it is just "Is a longer life better than a short life?" I think the answer is pretty obvious so I'm going to assume the question is "Is a longer life better then a enjoyable/fun short life?" I think that a shorter life that you have enjoyed is better then living a boring long life filled with regrets. An example of this I would use is Pope Benedict XVI who is around 85 today who has spent his entire live dedicated to the church/god and properly never done anything really fun in his life and if he died today I honestly think his life would of been pretty boring but if a man died at the age of 20-30 but had a fun, exiting and enjoyable life e.G Going to parties, travelling and having fun with friends I think he would of lived a better life then the Pope who has based his life on doing stuff for the church and not having any fun. So I would rather die young with a enjoyable life then die old with a boring life.
When I think of the idea of a longer life being "better" than a shorter one, I imagine a 100-year-old person who looks back on what they've accomplished, or failed to, and feeling regret. And then I imagine a younger person, maybe a 50-year-old person, who is instead looking forward and wondering what else they can accomplish. And so, I suppose I'm pointing to the old argument of quality over quantity.
So no, longer life is not better, but it's not necessarily worse either.
That may seem like an over simplified way of answer this question, but I can assure you I won't look back in fifty years and regret it.