I ordered the Spigen Slim Ultrafit for both my and my wife's Nexus 5s, thinking I'd just use them as stopgap cases until something better came out. They're cheap. But I am pretty impressed with them - extremely light and add almost no bulk at all to the phone. I wanted some protection but do not want to compromise the slim form factor of the phone, it is part of what makes it so attractive. This case doesn't compromise it at all.
I got the black version for mine and the white version for wifey. They are identical but for the color. I think they are a different cut than the clear ones, as these do in fact have corner protection. The fit is VERY snug, but I haven't found it to damage the phone. You do have to press the camera lens to remove it, but I don't plan on removing it so this isn't an issue to me. There were reports that the cutouts for ports and buttons were sharp but I didn't fine this to be the case on mine. All cutouts are perfect as far as I can tell.
I was planning on just using these as interim cases but unless something comes along that offers better protection without compromising the form factor of the phone I am happy to keep them.