Between the forty eight and nightster is their any difference in handling. What bike handles better.
Handling would probably be very close between them, based on specs alone. Only way to really know is to ride both side by side over a timed and closed course; measuring which is more confidence inspiring and drags hard parts the least.
I would also venture a guess that the new Super Low would eclipse both, partly due to the new wheels & tires being lightweight cast design/radial tires along with slightly longer travel suspension...! Add to that the slightly larger fuel tank and you would have a better cruising range as well. :s