When I DM, I leave the world wide open to the players to explore. There are hooks available to follow, political strife and intrigue, and spontaneous creation of the storylines. The power of the D4 may decide the characters actions, but if that area is a empty canvas, then I will fill it as needed.
As a player, I develop a character and then play that character as I see they would be. Generally, this doesn't make the character a perfect fit into a group, but rather they become an individual. They characters tend to specialize in one thing, but not push it to it's fullest. Just as a real person doesn't maximize any one thing about themselves, neither do my characters.
In either case, consistent rules are more important than following the letter of the rule from the book. I treat the books as guidelines, not "the law".
Mostly played D&D 3.5 ...some Twilight 2000 back in the day. I can come up with hooks and tie-ins to a story quickly, and am very flexible as to what's going on. As such, I tend to like a game that emphasizes fun over rules. Dramatic/cinematic story lines are a bonus, but not required...Epic is OK, but I'm not the type to railroad or be railroaded.