Kendall Marshall is the smartest North Carolina basketball player I have ever seen. (Full disclosure: I turned 26 this week, so savants like Phil Ford, Larry Brown, and George Karl were before my time). There may have been been better student-athletes (Tyler Zeller and Marcus Paige were Academic All-Americans) and there have been far more successful point guards at UNC (Berry, Lawson, and Felton have rings), but as far as basketball IQ, I'll make the case for Marshall over all of them.
But smarts can only get you so far: Athleticism has to carry you as well.