Theres is so much material here that it is difficult to narrow it down to a few examples. It is also difficult to find non-explicit versions of some of the exemplary tracks. I've included just a couple examples but you may want to visit Questlove's top ten hip-hop protest songs. to find more.
Public Enemy - Fight the Power
This track contains an un-apologetic performance from Chuck D on racism and oppression in America. You can find a detailed analysis of each verse here. This was included in the classic Spike Lee film, "Do the Right Thing."
A Tribe Called Quest - We the People
This track that was just released in August 2016 is more timely than you can imagine. I will let the lyrics speak for themselvs.
Topics: Current issues in Civil rights
Great Blog Post on Jay-Z's provocative and beautifully crafted video.