The Noctua NH-D15 is the objective winner of this comparison, securing two out of three spec victories. While the Arctic Liquid Freezer III 420 holds a significant lead in thermal management, the Noctua NH-D15 provides the most impactful advantage with a 9% better MSRP. This makes the air cooler the more cost-effective option based on the provided specifications, despite the liquid cooler offering a 40% better TDP rating for handling higher thermal loads.

Choose the Arctic Liquid Freezer III 420 if your primary requirement is superior TDP handling for high-performance systems that demand maximum thermal capacity. Conversely, select the Noctua NH-D15 if you prioritize a more favorable MSRP and are satisfied with the performance metrics associated with this air cooling solution. Each component serves a distinct need, with the former excelling in raw thermal headroom and the latter providing a more economical acquisition cost.