Citizens United would be my first target. Campaign finance laws in general coming next. A big root cause lies in ownership of "the free press," that one will be trickier, where does "news" stop and "entertainment" begin - and how would you ever regulate politics out of "entertainment" without impacting free speech? But, it's important to address if you want to really reduce money's influence in politics. Unfortunately, our legislators have been running the opposite direction for decades and the ballot box seems ineffective at convincing them to turn around.
Targeting capitalism, or communism, or pastafarianism, is pointless - they're big fuzzy clouds that you can't define, can't contain.