MGS because Splinter Cell it's more piloted experience you always know how to progress; you just have to follow the path using the right equipment an movements at the right moment....while in MGS you also have also to study the path to follow in order to not get caught....MGS has also better AIs. It's story and contest is less realistic while the action it's more. Of course both games must be played on an high-level difficulty otherwise they are meaningless.