I personally recommend Grand-central to you for so many reasons.Airfield is very friendly for flight training,general flying area is close-by meaning you needn't to fly longer to get there,the proximity of Rand with OR TAMBO always keeps you into a narrow zone so as not to disturb the traffic on 03R,the circuit pattern on the longer runway 06/24 if my memory is correct is tighter because it disturbs the glideslope for the big planes on final 03L/R.We used to have dinner at Harvard café almost every evening after doing night cross-countries on the way back to FAGC,that was good memories