Best fitting cases I've found is the Cruzerlite TPU cases and Diztronic as far as slim goes.
My only gripe is I've been using that dimple on the back of the phone which I've gotten used to and love, and when the case is on its covered up. There's some cases out there with the cut out but its just not the same.
Hey its a catch 22, some will use one, some will not. My phone is all white so finger prints are not an issue, however its winter here in NY so putting this phone in a jeans pocket will lead to a lil bit of blue getting onto some of the white areas of the phone, and dropping it will lead to well, a pretty bad day in all seriousness if ones in a rush pulling their phone out.
Its all preference I guess, my iPhone is in a slim TPU case so we'll see the next few days how I fare with my X and if I decide to use one of these cases I have. For now my X is catching a cold with nothing on because of this weather out here...lol.