An interesting point to think about is that MagSafe appears to be about 75% efficient (due to alignment of coils from the magnets), but also the battery size on

An interesting point to think about is that MagSafe appears to be about 75% efficient (due to alignment of coils from the magnets), but also the battery size on iPhones tends to be much smaller than competitor phones. For example, Samsung S21 uses a 4000mAh battery. iPhone 12 Pro uses a 2700mAh battery. At 75% efficiency, it's effectively like charging a 3600mAh battery. Both likely get a full charge every day. So, even with less efficient charging, you come out ahead vs. a Samsung device. That's also assuming efficiency of the actual charging bricks is similar. Apple tends to be known for high quality and efficient charger bricks, so it wouldn't surprise me if that has an impact.