My two cents:

Man is relatively Evil. We come out of the womb kicking and screaming. We are born with a desire to do what we want, when we want, and how we want. It's all about us. Did you ever seen a spoiled child? They are that way because the parents feed the desire of the child for more and more, and it grows until it becomes a monster. Greed is a mans greatest enemy, and yet so many embrace it.
The main reason Good exists in history at all is because of the way some people are raised. They are taught to be kind and generous - give to the poor, feed the hungry, etc. However, most of those people are religious. If you study religion, you find out the every good person is always rewarded in the end for doing the right thing. In the end, almost everyone who believes in some kind of religion is only doing what they do because they want to reach Nirvana, or Heaven, or some other place. That all is fueled by one thing - greed, the enemy of man.
I believe that very few people since the begging of time have been good just to be a Good person. They're always after something more.

Conclusion - Man is relatively Evil.