The Apple MacBook Air M4 wins overall with superior battery life of 18 hours versus 12 hours on the Dell XPS 15 per Notebookcheck tests, plus silent fanless operation. The Dell XPS 15 counters with a larger 15.6-inch OLED screen and more RAM headroom up to 32GB. MacBook Air M4 edges ahead on design and longevity per Wirecutter and CNET comparisons.