MM vs JP2 is a tough one for me. IMO it is the best B/W 90's pin vs the best of the modern Sterns.
It also highlights the differences between the two eras. Everyone can walk up to MM and instantly understand it. It has legendary callouts. I don't consider the art legendary, but it certainly fits perfectly with the theme. It lacks depth and variety, but at the same time even non-players love the game.
JP2 has incredible depth, a wide variety of unique shots - but honestly most of the call-outs suck (and I don't even care that it doesn't have movie assets). The art on all of the JP2 models is very-ordinary (and IMO below average)... it is too busy, and some of the perspectives seem to be slightly off.