My pick is always the more realistic scarcity model, like that of Decrits or eMunie for example, where supply adjusts to demand proportionately, not inversely proportionate like that of Primecoin.

In two years from now, Bitcoin has a very high chance of becoming "history" when it comes to functioning as a currency, and may only be used as a store of value by then (a commodity), because new things like eMunie will be able to process transactions in seconds, not minutes - so while not designed to be a "commodity" - it's function is very clear - to be used as a currency and it suppose to do that better than what Visa has already accomplished.

This thread is not about eMunie, so please refrain from going off topic and pigging back on other currencies (and it's nothing like Visa, btw).