I have a 48" and it has worked out well, mainly for helping others (never have had to jack my own Jeep!!). I would not go shorter, and with a lift, I might be looking for the 60" model.
They make an extreme model in 48 and 60 inches, but that one costs $20 to $30 more than the cast & stamped model.
IMO, being creative on how to use a Hi-Lift is more important than jack length. With a shorter jack, you can do the job of a taller jack most of the time, but might need to do it in several incremental steps.
