Gameplay. It's all about the gameplay. For example, Crysis. Crysis is eye candy. Sandbox 2 is as fun as it gets. The storyline, much like any game developed by Crytek, is boring and drab, very slow. They focused far too much on making a photo realistic game.
Now, Valve. Valve has been using the Source engine for ages. Sure, the graphics aren't as photo realistic as Crysis, but it makes up for it in gameplay. I feel like I'm in the story, and I feel eerie whenever I am about to go into a dark room. That's what I like, a story that can be like a movie and get me wondering, "What's that flashing behind the door?"
Sadly, because more games are focusing mainly on multiplayer, game originality has died off. A great recent example of a compelling storyline, is actually Call of Duty Black Ops. Sure, the multiplayer elements are the same old ones, but the story is where it appeals to me. I can't remember the last time I played a good story.
What I miss, is the old gaming days, where multiplayer was limited to you and a friend, and even then it was rather arcade-like, but it was fun. The days where a story was the make it or break it point of all games. Now it's been replaced to appeal to people who want better graphics and better multiplayer. Gaming has turned into a contest to see who can make the nicest, most advanced game. Simplicity is still the best at times. For example, the original Medal of Honor. Terrible graphics, basic FPS gameplay, but the design of levels and mechanics is still some of the best I've ever seen in a game.
Oh well.
I just now realized I've had a typo in my signature for the past 3 years.