I completely agree that Peercoin had the opportunity to become a much more efficient virtual currency, but it seems that ship has sailed. However, Peercoin as it exists now is not a fully decentralized currency and so is and was vulnerable to government intervention (during the SR era, for example).
Primecoin is not calculating anything particularly useful from a scientific or medical point of view (Cunningham chains).
Primecoin is not calculating anything particularly useful from a scientific or medical point of view (Cunningham chains).