JP and JM - obviously 2 out of 3 I have - are pretty darn comparable. I would say, in terms of gameplay, JM destroys JP. JM has so many shots going for it, whereas JP as 1 ramp and 1 "ooohhhh ahhhhh" toy being the TREX. JM absolutely annihilates JP in terms of fun factor and replayability.
JP > JM in terms of appeal and looks. The translite for JP may possibly be one of my personal top 5 of all time. Just all colorful, to the point, and HOLY CRAP a TREX!!!! And of course with toys, JP >>> JM. The TREX vs the glove = easy win for the rex. JP also wins in terms of soundbytes - the dinos rock the house. JM does have some good bytes and music, but the fact they're all impersonators = THE lose.
If I had to pick again which one first, JM for shots and fun. JP for "ooohhhhh...ahhhhhh!!!" and the TREX toy ALWAYS being a hit with people experiencing pinball for the first time or coming back from a decade plus hiatus.