One of the best lines for Sicilian Defense is called the Najdorf, and it's often used by higher-rated players because it hasn't been defeated. The Sicilian Taimanov is another good one. However, I wouldn't recommend these lines to a beginner because they're highly complicated. If you're just getting started, it's best to play a line that doesn't require so many variations, because it's easy to get overwhelmed when it's all combined.