I've never really thought about this before. Our small Garmin at the helm was always north up, so that's what I got used to. This summer I added a Lowrance CP/radar mounted in the companionway, and it defaulted to course up. I find I like them both, they each seem to have their advantages. What's a bit unnatural though is to look at one and then the other, so I'm inclined to set them both the same. North up feels more natural to me as far as navigating goes. But with radar overlay I think course up might be more intuitive, especially with respect to bearings to other boats and radar targets. Curious what others find best.