I'd go with 1. Wilt 4.44 2.Bill Russell 4.26 3. Garnett 4.30, just because they have the highest career APG. Even though Garnett is listed at Foward, only Wilt, Garnett & Kareem are the only guys over 6'11 to even average over 3.2 APG for their career so they have to be way up there on the list.
However per 36 minutes I haven't found anyone with better numbers than Walton at 4.3 which is higher than Wilt, Russell, Garnett & Kareem.
So its basically Celtics, Celtics, Celtics, with a couple of Lakers mixed in there.