I'm conflicted, since I liked both a ton.
As to what would make it worth playing in the current marketplace? Good game mechanics, an engaging story, choices that matter (ie. not like Mass Effect 3 ending) and plain just liking System Shock, SHODAN and the scifi theme.
Hard to say, are survival games still in?
For me it was the mix of game mechanics and story. There was one huge level to explore (well with loading screens between the different decks), a light rpg system for your character (no jack of all trades), the limited inventory (so you cloud not carry everything and had to store your stuff somewhere else), the small stories and messages of the other crew members and the one thing that was quite new in fps games, you was able to climb on larger boxes or ledges.
Well, Shodan, i am not sure about her. I know she has survived in the implants of Rebecca, but the third time as villain might be a bit boring.
But maybe it is just the spacezombie thing. For example i did not really like Bio Shock 1, which was basically System Shock 2 with a different setting (minus the rpg part, the inventory, without Shodan and another ending). Dead Space on the other hand was great, it still lacks Shodan and the huge single level, but the rest is like in System Shock (oh and it has a similar story like Mass Effekt but a far better ending).
Poll