Fantasy certainly may appeal to more people, but my point was that it's personal preference. In that sense, saying one is better over the other cannot be true.
Number of sales also doesn't prove anything either (think Brotha Lynch Hung vs. MC Hammer, or BMW vs Honda). I'm not saying Halo is MC Hammer & Lynch is Killzone either, just trying to show my point.
I do see what you're saying though, and I'm not argueing anything other than the fact that it's personal preference.
"Dark, sinister, realistic FPS" is exactly the type of game I want to play! Plus, I'm an adult too so I tend to like more adult oriented shit (like naked bitches, beer, dark/sinister games, blood, abortions, etc.)