For topics like this, I recommend making use of a unit called "quality-adjusted years of life." We can never ultimately reduce instances of death except by reducing the birth rate or breaking the second law of thermodynamics.
Where the limitation from laws of thermodynamics is a relevant idea, quality-adjusted years of life isn't.
If you allow quality to be greater than 1, it might be. Computation becomes uncertain, though.
Causes of death such as malaria and hunger are certainly worth allocating resources towards preventing, for today's results-oriented philanthropist. It's almost ridiculous to realize we can put $1000 towards mosquito netting and save a human life. However, these kinds of things will eventually run out of low-hanging fruit, especially as countries become more developed. By advancing the adoption of certain key near-term technologies just a little sooner, we can make rather significant gains even in developed countries where the causes of death are more complex and occur later in life.
According to Brad Templeton's executive summary of the case for robotic cars:
Anything in the range of a million people per year definitely qualifies as a holocaust! And yet this is actually a fairly small percentage of the world death rate (about 57 million per year) overall. (Most deaths are caused by heart disease or infectious diseases.) Nonetheless, self-driving cars strike me as an attractive initial goal for the following reasons:
The robotic exo-suit is another near-term source for dramatically increased GDP -- a person wearing one can perform manual labor tasks with greater endurance and reduced danger of physical injury, without undergoing painful physical conditioning. It can delay forced retirement age, as a feeble body will no longer be an obstacle to a number of tasks. Furthermore, powered suits may prove the key to truly comfortable hermetically sealed environments -- something that can be very handy when old age hits and your immune system declines. It can also be useful for keeping infectious diseases in.
The artificial heart is something else that can reduce instances of death significantly. We are kept alive by two pounds of throbbing muscle just waiting to explode on us. Removing that risk from the picture would have a huge impact on the death rate in the developed world.
Another huge risk-reducer would be wider adoption of robotic surgery. This enables surgical interventions to take place under far more controlled circumstances, without hand-tremors and human error to complicate matters. As surgery becomes more safe and noninvasive, it can be used for preventative maintenance, rather than being conserved for when something is going wrong.
Cryonics and robust rejuvenation treatments still are very significant from a life-extension perspective. But proof that they will work is not necessarily going to be available until it is too late to convince people (in this generation) to start allocating significant resources to them. A better strategy might be to invest first in these less radical technologies (while still maintaining a healthy activist base for life extension memes) and use the economic gains to jump on the growing life extension market as it starts to open up.
Another thing to bear in mind is that cheap, accessible robotics can lead to cheaper, more accessible cryonics and life-extension drugs. These things tend to synergize. A factory where the workers are equipped with exo-suits can produce chemicals, drugs, and mechanical parts more quickly and cheaply. The more easily a new piece of robotic equipment can be prototyped and tested, the more likely it will see use sooner, resulting in the earlier introduction of safety and economic gains for humans.