McLaren 675LT vs Porsche 911 GT3 RS - Which Is Better?

In this debate thread, we'll compare and contrast two of the most potent track-focused supercars on the market: McLaren's 675LT and Porsche's 911 GT3 RS. Which one takes the crown? Weigh in with your expertise and share your driving experiences to help us determine which is better - or are they even comparable?