And the most special thing about Dues Ex was the storyline. It was prominant in Half-Life 2 (and regular Half-Life) and just about every game that has been really gripping to play.
I think, more than focusing on a genre of games, you need to make some genres have certain features.
For an FPS (for exmaple) you need to have great graphics and a gripping and envolving storyline.
For an RPG, one thing that RPG's today dont really have a fantastic graphics. ElderScrolls Oblivion being a coming exception.
I think that all genres are great and it is all about the time and love put into creating the game that matters.
(in real answer the the question Accra1Programmer posed: I love MMORPG's, but there are a whole load of awesome ones just coming out now).