Communism has never worked out, because it has never actually been in place properly. What we think is Communism, is actually a skewed version of Communism, because people are not even equal if there is a dictator in place. I mean Communism in Russia was just used as a tool to control the proletarat.
I think I would choose Communism though, because Jesus was probably more of a Communist than a Capitalist and if Communism was carried out correctly it would be a lot better. (I'm not a Christian btw)
I don't think Capitalism is sustainable at all, it just fuels the greed mentality and just brainwashes everyone to buy. It turns Christmas time into something evil and encourages everyone to compete with each other at the price of health (fast food chains), the environment (using up more resources making more and more crap.) and our morals, among other things. So Capitalism doesn't seem like the way to progression.
Neither but since pick socialism I'd opt for capitalism.