What is the purpose of stroke prevention?

When you break it down the real reason is actually to save brain cells. Prevention is only one way to accomplish this. Another way would be to stop the cascade of neuronal death due to glutamate poisoning, excitotoxicity, non-opening of capillaries due to pericytes.

So which way can save more brain cells?
ASA or NSA, what is your answer?

After that comes the repair of damaged cells - mainly via neuroplasticity, which needs a lot of research yet to document how to repeat it. We know it works but we don't know how it works.
Then would be the replacement of dead cells via angiogenesis, neurogenesis and maybe stem cells