for me, it depends on how soon i plan to play him.
if he is gonna start frosh or soph, i would value speed first.
but if he can sit and grow for 2 or 3 (with rs) seasons, that same 62 guy will be closer to 70 by his 3rd (as a true jr) or 4th (a rs jr), and then you will really appreciate having the higher cores.
conversely, the 72 guy may be in the high 70s by then, but there is a deminishing return at the high end of speed, he wont gain as much as the 62 guy over the course of his player growth, and there is such a thing as wasted speed in this sim i think. that is, speed 90 plays about the same as speed 75 anyway.