Yep following on with Emirates better On Ground service, you get chauffeur services in both DXB and JNB but only AUH with Etihad, this may or may not be important to you but should be a factor. Also Emirates has a lounge in JNB.
Seat wise I havent tried the A332 J class, but the 77W of Etihad is one of the best J class seats out there. I think the A332 one is a little narrower.