The Withings Pulse is inaccurate in cold conditions, can only measure your heart rate while standing still and cannot monitor it continuously. The Basis, on the other hand, cannot measure heart rate accurately during impact or high intensity exercise (e.g. jogging, aerobics, resistance training/weightlifting) so the Loop wins here by a significant margin, also meaning that it's calorie count is more reliable.
Loop is for people who train on regular basis and already adopted themselves in healthy living. Others like fitbit jawbone etc are for lazy people who have not much to do with fitness. Show me one good example fitbit calculates calorie burn correctly in weight lifting or crossfit exercise I'll burn my loop and get fitbit. But let me tell you one thing that will never happen unless they find a way to measure your pulse