I have both of these right now as my only two pins. DW is newer and I'm enjoying it more than JD. They are both very different kinds of games. Dredd is a mode-based game where the modes are all timed. It is a harder game but can be made easier. DW is all about points and multipliers, its more old school in that way. There is less variety in DW but possibly more depth in the strategy.
They're both awesome games but I think I'll hang onto DW much longer.