Socialism is essentially when a government takes from those who produce and distribute to those who do not. That's not what Christ taught or endorsed.
Jesus taught to willingly care for the poor and less fortunate. He also taught against greed and putting too much value in material wealth. We leave it all behind when we die anyway, so we are to be good stewards of what we have and use it to help others as best we can.
Choice is the main flaw in the "Jesus was a socialist" argument. Jesus told the rich man who wanted to follow Him to sell everything first. The rich man was too attached to his wealth and chose not to. If Jesus was a socialist, He would have just took it against the man's will. Instead, He used the situation to teach that attachment to things and wealth can cause us to miss out on greater things.