The roads mentioned by OWN are, I think most definitely the road " less travelled " at least according to my experience.
Personally I had hardly made it a point to travel these but after trying it over the last couple of years I have been drawn to it more.
Here are some of the reasons why :

These lions were seen on the northern part of the S128 at the Rietpan watering hole in July 2009 sitting in the shade of the only tree to be seen in the immediate surrounding. A visit to the same place this April showed no sign of the tree. Probably the work of an elephant.

There were 2 females and a fairly youngish adolescent male were to be seen. The obvious extra dimensions of the stomach of the the female that is standing can be attributed to this :

They had killed a zebra some time earler and had clearly had a feast of it close to the edge of the watering hole.
Not far from them the clean-up crew were patiently waiting only after having a charging lioness reprimand them for not behaving.

First time these roads had produced a cat.
Since then like I said I give these roads a go.
In August of 2009 I decided to go for a quick just over an hour drive before gate closing. Hit the H10 then left onto the S129. Not seeing much as I was doing a fair speed I rounded a bend and amazingly in front of me stood a SERVAL !!
I had time just to drink in the sighting as seeing that I had rather surprised it I watched in awe as it slinked its way into the tall grass. No pics but my 1st SERVAL

. One to put in the memory bank
Thrilled with the sighting I next came upon these two just standing around the little afternoon shade that was present.

Continued to the end of the S129 and the left on the S128. Not long thereafter I came across one of the biggest herds of ellies I have seen in the Kruger. There were in excess of 40 of them.

Continued on and passed the S29 turn-off and not far from there, believe it or not a 2nd SERVAL in the space of about an hour just on the side of the road. It got off the road and stood on a mound staring at these human invaders before doing its best to be invisible in the long grass.
With time & light running out I managed to fire off my camera as best I could. Not the best of pics but I managed to get it on record.

As I they are rather shy & elusive especially if startled it lay in the grass observing us.

At the same time directly on the opposite side a BBJ was doing his rounds.

.
Had watched the serval for about close to 10 minutes before I had to push to camp. More fortune greeted at the Sabie bridge as a leopard was marking the concrete pillars just before the bridge.
As mentioned have driven these roads more ever since then and the next day got more action at Rietpan on the S128.

Rietpan watering hole.

A black backed jackal that had been sheltering itself within the depression of the watering hole and bolted on our arrival .