Also depends on whereabouts you stay. They are on opposite sides of Johannesburg. All the reasons stated above are totally valid but i did my training at Rand because I stayed out that way. You don't want to have to contend with Joburg traffic and fuel cost by having to drive from the East/South all the way to Midrand.
I actually loved doing my flight training at Rand...many good memories. I would recommend Rand purely because that's all I know with regards to training. There are some good training organisations there but also some not-so-good ones!
There's much more open field around FAGC in case of EFATO.
Was always a 'heart in mouth' moment at Rand in a Cherokee 140
There are zero options so must agree with you there.