For under R600, you won't be able to find anything better than the D-Link DSL-2750U / TP-Link W8960N.
Cisco/Linksys makes good enterprise products, but I'm not very fond of their home & office products.
In SA the broadcom ADSL chipsets give you the best SNR margins compared to the others. Just be careful with TP-Link units, because some models (those ending with a 'T') does not use broadcom chipsets - instead they use TrendChip or something like that.
Lately I've seen many D-Link PSU issues (or at least I suspect the PSU being the culprit), but I think that is bound to happen to someone when you have such a big community. This is why I run all my equipment off an awesome APC UPS to just reduce the chances of losing components due to PSU failures caused by spikes/electrical surges.
Like recently on Twilight Forums one guy posted that he had a DoA (dead on arrival) Corsair CX430v2, which he returned and then he received another DoA Corsair CX430v2 unit! So issues can happen to the best of brands.
Lastly, if you don't need WiFi and don't mind having lots of routers/equipment, then you can buy like a cheap D-Link DSL-2500U and a 5 port 1Gbps switch, which would cost you less than R600 in total.