I like my Sear's Craftsman rear wheel drive mower with a 6.5 horsepower engine. I can't compare it with others but it seems fairly trouble free based on two years use, and the price (bought for less than $300) was the best I could find. I don't mow St. Augustine, mostly patches of hybrid bermuda, zoysia and fescue. Parts of the yard have a moderate slope. If the lawn is still damp after night time watering, the traction weakens a bit on the uphill runs. That seems due entirely to wheel slippage on the grass and I expect this would vary little with another brand. I mulch and in some areas the grass is very dense. In those places, I use the standard technique of slowing the advance so that the cutting blade doesn't need to take such a large bite on each rotation. It is also recommended to cut a narrower swath to reduce the load on the engine. I haven't needed to do that.
Incidentally, if you bag the clippings, Consumer Reports suggests that the rear wheel drive units have better traction when the bag gets loaded. Makes sense.
SJF