The Bible doesn't dictate any form of government. In the Bible God does not dictate the shape of society. He does not seek to form a "perfect" society, because no society is perfect (since it is a society of fallen humans). He rather speaks into the shape of society as it exists in those times and encourages his people to live holy lives in that society. God never dictates an ideal kind of government (monarchy, democracy, socialism, etc. Every political system is flawed.
We would have to judge more by history and by situation than by anything "Christian." Monarchy works well when the king is both good and responsible. Democracy works well if the people are moral and community-oriented (as opposed to rights and self-oriented). Socialism works well (theoretically—we have yet to see a socialistic system work anywhere) if the leaders and people are genuinely interested in the good of all rather than centered on advantages to oneself. I'm also not convinced that theocracy has ever worked well anywhere.
Every system has its pros and cons, strengths and weaknesses. They are all vulnerable to abuse, as we have seen many times in history.
In an ideal sense, government of the people, by the people, and for the people is a great ideal. It's only people that wreck it.