Is public property more valuable than private property?

This week, mostly when we had our discussion right after finishing Style Wars, one of the biggest arguments that we had, I think, was about whether or not private property was more valuable than public property. I think the general consensus in the room was that the graffiti on the outside of the subway trains were beautiful, artistic, and inspiring, but the main difference in opinion existed about whether or not we cared about the legalities of it. Maybe we all do little things that 'break the law' (I'm sure at least that we all jay-walk), but we all also understand the fine line between actual criminal activity and harmless habits. People who were for self expression through graffiti claimed that since it was public property, it didn't belong to one single owner, and that the artists had as much right to paint on it as others had to ride on it. Conversely, people against graffiti on the trains used the argument that defacing private property (like someone's house) would be disrespectful, and would cause justifiable anger. Is defacing public property less 'bad' than defacing private property? Its hard to say, public property is something that all of us pay for, including those who don't like graffiti. We all pay for the right to have access to efficient, public transportation, but do we all also pay for the right to have clean, efficient, transportation? Graffiti is meant to speak to other writers, but when this exclusive group of writers compose an incredibly small minority of the people who pay for trains, is it fair to impose their art on the majority that either don't care or don't want graffiti? Likewise you could argue that graffiti is a form of self-expression, and it was probably one of the only artistic outlets that early writers had available to them. It's easy to form strong opinions on this topic, but there are always two sides to a story. Its sort of like Nanny and Janie, I'm not really sure who or what I sympathize with.