Worst was Aaron Burr, by default.
I'm trying to think of a case for best. Truman saved the US from Henry Wallace becoming president. Hannibal Hamlin had the best name for any VP. Nixon made the office very active and visible, which all of his successors have followed to the present day (Adams tried to be highly visible, but was rebuffed by the Senate, and mostly ignored by Washington). John C. Calhoun wasn't good, but he fought with Jackson, so, there's that. Gerald Ford was basically appointed to the position so that he could clean things up for the collapsing administration.