One of the problems with Lanseria is the inordinate amount of time and money that can be chewed up taxiing over the horizon and into the dim blue. That's without holding at the holding point for a couple of aircraft on a long final.
Once you're airborne of course the instrument facilities are pretty good although who has any idea what the booking time for an approach and go round and rejoin might be like?
Advanced training as in IF from Lanseria perhaps but basic training up to PPL and even initial twin rating at least, then I'd stick to Grand Central. That airfield can get quite interesting at times when it's busy.There are a couple of schools there both of which I think run ground study courses. Of course in the glory days Rand used to be the gold standard. If you could hack that place on a busy circuit day and not stray into controlled airspace, then you were on your way. But the Transvaal Aviation Club was a flying club in those days with its own aircraft and the right of admission was reserved and executed sufficiently to keep standards fairly high most of the time.