Olive oil is processed and so it loses most, if not all, of its health benefits. Sunflower oil is healthy, as you would expect, since it comes from sunflower seeds. The sunflower oil you buy in the supermarket is processed into something more chemical than food, and is more likely to contribute to heart disease than any health benefits. Olives should be much easier to deal with than seeds, so maybe the processing isn’t quite as bad, but I wouldn’t bet on it without looking it up.
Even virgin olive oil isn’t guaranteed to be healthy. If it’s been exposed to light or heat for any period of time, then it’s probably at least partially rancid. I avoid ones in clear bottles and look for a best-before date that’s as far in the future as possible.