I'd like to compare the rules between these two games, to see which has better rules.
hopefully someone with more knowledge will chime in and tell me what I don't know.
SM has 4 main modes (Goblin, Sandman, Venom, Doc Oc) which could be compared to ST 6 modes (DTD etc.) each of which can go three deep. With SM modes you can run the modes all at the same time (is this good?) with SM each mode has a dedicated area for example Goblin is the Goblin targets (etc.) and as you get to level 1,2,3 they get harder or require more shots.
With ST each mode the shot area is more free form although I don't know exactly Eskaybee tells me that each mode has a certain rhyme or reason why it the lit shots are lit in that particular shots for that mode. Modes can not be run together and you can pick in order to get more level one or more depth in each mode.
ST has some stand alone modes such as Klingon and Vengeance battles, as well as some GAT special scoring and also has medals and the three tier wizard modes.
SM has several timed modes such as Bonesaw, Rescue MJ, Daily Bugle (etc.) which I don't think have a correspondence in ST. Also two wizard-like modes.
I happen to like the GAT bonuses, but I believe I'd prefer more modes such as SM has with the timed modes (as well).
I am not quite sure of the scoring and strategy aspects of either pins. It's said that SM really took off once the rules were completed, but I am not sure what that involved.
One criticism to me when I had SM was that I would play the four modes as they came up. I really didn't go into a game and say I'm going to try to not start Venom or try to concentrate on Goblin (or any real strategy) I did watch some of the SM tutorial and saw that you should try to bring a timed mode into the other modes.
To me, while I do like dedicated areas of the PF like SM (also like IM), at the same time (IMO) those games tend to play out much the same. Meaning just try to get as many of the modes completed and progress to whatever wizard mode possible. With ST (again I don't really know the rules) it seems as if there is more paths (possibilities) to play, such as going three deep or to go all level one modes.
One more aspect, SM has more inserts (not only major shot arrows, but also spider inserts and white web inserts) so in a way SM gives you more information and more things to aim for. ST has major shot arrows as well as combo inserts.
As far as the wizard modes, have never really got that far so I don't know or can't say how they stack up or which game has better rules.
I do know the perception is that ST is so-so for the rules (some say chopping wood or just 'shoot the flashing lights') others say ST has very good, deep and thought out rules. While most people seem to say SM is another example of Lyman Sheats Jr being the best and the brightest (some say only Stern programmer worth buying).
Above is just my view from a punter (what I mean is a guy who know the rules of modern pins, but not one that ever gets too deep into the game to know exactly how good or bad the rules are).