I have owed both, at a time my only 2 pins. They look similar, but play differently. SM has great shout-outs, amazing flow, the doc-ock shot is fun to get down and mastering the missions will keep you coming back. Great pin.
Star Trek, which I still have and love is a favorite, but it is punishing. You have to be good to get the shots down, the warp loop is amazing fun but hard, novice player walk away cause they loose fast. Now with the new code it looks amazing, light show show during play is over-the-top. The code is almost finished, just needs a little polish, but really solid right now. Maybe buy that routed SM and try to hold out for an STLE
Both games are great, can't go wrong with either...