Bitcoin, Monero, and Darkcoin all have the same large problem.  The ASIC came too soon for Bitcoin, so a wide distribution, which is required for currency, is a fraction of what it would have been if off the shelf hardware could have been used for even a couple more years.  Even Satoshi has quotes talking about a "gentlemen's agreement" to not use GPU miners, heh.  Whether the Bitcoin distribution is good enough for it to succeed in the long run is unknown.

For Darkcoin, having block rewards set to 10x what they're supposed to be the first day or two, then reducing coin supply afterwards from 80 mil to 20 mil is a show stopper.  Does anyone really think Bitcoin would be as big as it is now if Satoshi pulled off that blunder?  The answer is an obvious no.  People would refer to Bitcoin as "Scamcoin" if  Satoshi had done that, and the market cap never would have broke a dollar.  Every other coin that's had a blunder that huge on launch, such as "GPUcoin", was relaunched.  The fact that Darkcoin was not relaunched after a mistake that huge is nuts.

Then for Monero, just like all CPU mined coins, trying to mine any with the botnets on it is almost impossible.  I tried mining Monero the third day it was released with two Haswells and got zero.  I don't think it even had botnets on it then.  Ironically, Dogecoin probably has a better distribution than everything else in the top 10.