Definaly deus ex. Game play and graphix are awsome and its not only all bloodshed but u have to use ur logic as well. u also learn a lot about govt ideals and how to run govt and its a wonderful game!!!!!!!!!!!!!
Chalk another one up for Deus Ex. I agree with you silent_bob, that first mission/demo doesn't quite catch the air of the full game. I think of it as exactly like movie trailers should be, enticing concept but not handing over the plot, saving the best bits and lines for the full title.
They do play differently, but I would get Deus Ex regardless of what kidn of game you like. That game is truly incredible and will keep you occupied for many weeks. My friend has passed that game over 5 times because its so different everytime you play it.