In this posting I will try to give some advice about how to choose the right spatial data sources. I will focus on legal issues. As you will see the conclusion will have to be one based on more than one factor.
As far as I know very few people, if at all anyone, have been imprisoned for breach of copyrights pertaining to spatial data. We have often heard about how sharing digital movies may lead to high fines and imprisonment. Even linking to copyrighted material might lead you into such problems.