#1 for me would typically be NGK. Having said that, a lot of the vehicles I've had have used NGK, or Denso, as OEM. Just from a brand standpoint, I prefer NGK over Champion due to, what seems to me, better build quality. Looking at both, I've noticed the machining and finishing such as the threads, on NGK seems smoother. The center electrodes 99.9% of the time are centered well and the side electrodes are attached cleanly and square with the center electrode as well. Many of the Champions I've seen appear to be not quite as well made.