I like all types of heads, but I use the detailed ones more often than the plain smiley. I don't think that doing so detracts from my creativity. I decide what type of personality a character should have, and I choose a head that is appropriate for that. I don't just say "Well, time to choose a random head. Ah, an angry face. I guess this guy must be angry." Instead, I'll say to myself "Self: this guy is one angry dude. Perhaps the smiley isn't appropriate here. Ah, here we go! An angry face!"
I do still like the classic smiley though. I use it for my generic Falcon figs (they just don't look right with anything else) and also if I'm using a hairpiece (though I do like a bit of variety when it comes to mouth shapes and eyes sometimes).
I've found that the Luke Skywalker face and a lot of the Harry Potter faces (just eyes, eyebrows and a mouth) can all be used to represent the same person with different moods, and I think that's great. For example, you can use the Luke Skywalker face when your character is calm, the Tom Riddle face when he is mildly annoyed, or Lucius Malfoy's head for when your character is angry.
"Always do what you want, and say what you feel, because those who mind don't matter, and those who matter don't mind." ~ Doctor Suess