The Big Dipper lands himself in the top spot on this list because his routine had, well, a sense of routine-less-ness. A notably horrid career free throw shooter with a 51 percent average, Chamberlain had many free throw shooting advisers over the course of his 14-year career.
He was known to have tried a variation on the hook shot, short dribbling routines, softer follow-throughs, more arc, less arc and even the Barry-esque under-handed variation.
One of the more unsubstantiated, but not too implausible charity attempts—probably due more to Chamberlain's Paul Bunyan-like stature on the court—was that Wilt tried, but more likely considered, dunking or laying it in on a few occasions. In fact this prompted rule changes that stated that a player could not cross the foul line in order to shoot his free shot. But just attempting it!
If that's true, and there's no film footage to back it up, the 7'1" 275 lb. Chamberlain would have undoubtedly been the first and only to attempt this feat, and for that consideration alone the late great lands himself at the top of this list.