Think of Ella Fitzgerald's voice. It is distinctive--you recognize it when you hear it--but not eccentric or excessively mannered. It is capable of many different special effects, growling or scatting, but at its core it is relatively pure and "straight," at least whenever she wants it to be. She has a wide range, but she also knew where the sweetest part of her register was and how to exploit that.
I love Sarah and Billie too, but they don't have that quality of neutrality or purity.
Now think of your "instrument," your writing voice. It can be distinctively yours without being at the extreme fringe. There's plenty of room for personality even in a seemingly neutral style. You don't have the exaggerate your differences from other writers in order to be original.
Mannerisms that are shared mannerisms, those that every singer uses, are even worse, because they sound at once mannered and non-individualistic. Like the old joke: "How many jazz singers does it take to sing 'Summertime'?" --"All of them." One example might be the parenthesis in the title, like "(Un)queering the Renaissance...." or "(De)Constructing (Dis)ease." Very clever, but clever exactly in the same way everyone else is. I'm very allergic to that; you might have your own preferences and (dis)agree with me, but either way it's something to think about.