When you evaluate the two currencies or even more, you should take Gold price as the deciding factor instead of comparing with the otherdigital currencies. Because BitCoin new-found demand has been happening due to the China factor, where more people are buying because of the instability of their currency. That trend may dissipate quickly. Ideally, if a currency performs over the 'world inflation index' (i imagined this index where we have to take the average of all the nations) and still it performs better, then you need not worry. Or else, the simple calculator is gold. But not with other cryptos.