If you only watch a handful of episodes, make them these. These are widely considered some of the greatest episodes in the history of television animation.
Season 8 works well as a binge-watch, but it is also highly episodic. You can jump in at almost any point. If you are watching a "DTHrip" or standard digital file, ensure your video player supports the usually found in these rips to ensure the dialogue is clear—the dialogue is dense and fast-paced, and you don't want to miss the background jokes.