Instead of going through everyones differing opinions and comment, I'll just start out with this. Sorry for my half-hearted lack of participation.
Communism:
Yes, Duke Juker is right, in an ideal world, Communism would be best. But obviously, this isn't an ideal world, and there is no way it can be changed to work with communism. In this world, there is always greed and selfishness and too many opinions. Because of this, government corruption is ALWAYS going to happen. ALWAYS. Look back through the history of every communist country there ever was, and you will believe me if you allready don't. Now for capitalism and socialism, goverment corruption is much less frequent and it is hard for a leader to openly cause disruption without being booted out of office.
Now of course I don't mean trivial stuff like Obamas health care making republicans mad and fueds started and all that opinionated crap. I could almost consider Bush an example here, considering he cost us millions, but I'll not be so cold. After all, my Grandmother might disown me.

Socialism:
Now im not an expert on socialism, but I do know some stuff. Socialism doesn't appeal to alot of people because of the fact a truck driver will make around just as much as a lawyer. It doesnt seem fair, but to me it seems like socialism is best for a multitude of reasons.
This is not a very strong reason, but socialism works. Look back at all socialistic countrys, like scandanavia for instance. There is almost no poverty there. Now what makes sense to you, some people crushing others, gaining power and mney to spend on luxurys, not caring that many people are suffering financally because of them, OR, everyone still able to advance in their jobs, but with the "social" part of socialism, everyone get the money they need. No people living off disability payments, everyone gets what they need. Also givs us less money for stuff we dont need, like consoles, games,extra tvs, that stuff. Which, in my opinion is better. I can live with just the computer. thats it. I could care less about the tv, radio, consoles, ipods, cell phones. Summary of socialism: I would rather no one be poor and almost no one be rich than some people are rich, alot of people are poor,and middle income people are always suffering from pointless conservative arguments.
Capitalism: I don't have much to say here, because I basically explained it all in the socialism section. I just feel like it is more unfair than it is fair, Maiden. Maybe thats screwed up, idk. To me, being equal would make our lives alot less pointless.
EDIT: I realize this post is a little disorganized. Please Bear with me.