Knots IS the best measurement for ocean measurement for most of us Old timers who grew up before GPS electronics, but for those who have learned their marine experience sine then, a number of different measurements take hold, he most common is probably MPH. I agree its' whatever you're comfortable with, but its sad to see the true measurement be pushed aside. I think that as long as you are proficient in your conversions (i.e. 1 knot is approx. 1.1515 Miles which is approx 1.6 Km and 1 knots is approx. 1.84 km) then you have all you need.
Oh and you may not USE your paper charts, but if you don't have them on board and you are not able to read them, take a bearing, triangulate your position and plot a course, you shouldn't be out there.