On an APS-C, I found the 85mm to be a less useful focal length for anything other than a dedicated outdoor portrait lens. If thats what you want it for - then it is leagues ahead of the 50 1.8 for focus and build quality. However if you want something a bit more versatile, but still a strong portrait lens on your crop, I would stick with the 50mm FL.
My 85 1.8 was not very sharp wide open, and displayed some CA in the OOF areas (cant remember what that is called), but sharpened up very nicely when stopped down even a little.