BITCOIN

Bitcoin's valuation is determined solely by how much speculators buy and sell it for. Consequently, the value of Bitcoin yo-yos wildly from day to day, and it is impossible to set prices in Bitcoin. For example, if a widget were to cost US$30 one day, US$200 three weeks later, and US$50 the week after that, no-one would use USD for doing business. Any modern product or service requires a complex supply chain; since supply chains collapse if prices swing wildly, Bitcoin is utterly useless as a medium of exchange. Interest in Bitcoin has been solely as an object of speculation, not as a viable digital currency. 

ZENCOIN

The Zencoin's value is tied to the performance of 22 international currencies from major economies on five continents. Even if any one of these currencies were to collapse, the value of the Zencoin wouldn't be affected greatly. The Zencoin has even been designed to withstand swings in the value of the USD. As such it the Zencoin is stable by design, and it is possible to develop a sophisticated and viable economy using Zencoin alone. It is entirely possible that major corporations and even nation-states will one day use Zencoin as a medium of exchange to safeguard against exchange rate fluctuations between traditional currencies. 

BITCOIN

Even key players in the Bitcoin industry admit that Bitcoin mining is environmentally destructive. Bitcoin are 'mined' using specialized computing rigs, which consume enormous amounts of power. TechCrunch reports that Bitcoin miners consume $150,000 worth of electricity per day. It is an egregious waste of resources to commit this much computing hardware and power solely for the purpose of enriching prospectors. Surely there must be a better way of increasing the supply of the currency than producing as much carbon dioxide as a small city. 

ZENCOIN

Increasing the supply of Zencoin does not involve any heavy number crunching. The Zencoin money supply can be regulated to prevent inflation or deflation. Since the Zencoin is issued in exchange for legal tender rather than mined, the Zencoin does not result in massive amounts of electricity and computing power being wasted on currency creation. The Zencoin is possibly the greenest currency in the world as it is not printed on paper, nor minted in metal, nor extracted by dint of raw computing power. 

BITCOIN

It is not completely clear who profits when Bitcoins are mined, although we do know that some of them are criminals. While supporters of Bitcoin claim that Bitcoin is democratic, the complexity of the technology and the murky nature of mining mean that in reality regular users have no say in how Bitcoin is regulated. 

ZENCOIN

Then Zencoin is issued by a transparent democratically managed organization with open-book accounting. Anyone with time and interest can become involved just by becoming a member. While you may not always agree with how the money is used, at least you know where it is going.

 [...] here we are in a world of high information technology — and people think it’s smart, nay cutting-edge, to create a sort of virtual currency whose creation requires wasting real resources in a way Adam Smith considered foolish and outmoded in 1776.

-- Nobel laureate Paul Krugman on Bitcoin