Which is you interested field of study? How strong would your recommendations be? Were did you do your undergrad/master and in what field?
While it is important to ace the GMAT, the GMAT itself may not get you into the program if the rest of your application is weak (e.g. poor recommendations and research match with the school). Conversely, if the rest of your application is strong, the weak GPA may be less of a hinderance (although the weak grad GPA could still be a concern). Also, for PhD programs, there is no widely accepted tier-ing of schools. So it is hard to say which tier you should apply to.