I guess that just by weight of numbers the three NSW 2-8-0 classes would need to be considered as the top freight locomotives on that system. But I'd expect that, from the earlier discussion, we need a bit more explanation of thre three types and their features.
The original T class dating from 1896, later the 50 class had 290 members built, but ten were commandeered by the British Army for use in Belgium.
The TF class of 1912 had many changes from the T class design. These included flanges on the second coupled and driving wheels (hence the "F"), knuckle jointed coupling rods and a larger tapered boiler (much like that on the NN (later 35) class. These became the 53 class, and 190 were built.
The K class built from 1918 included all the changes of the TF but with Southern Valve gear added, and 120 were built.
Part of the problem was that E.E. Lucy was not a designer and did not arrive (as Stanier did at the LMS around thirty years later) with detail drawings of the parts that made GWR locomotives a success. This was despite him knowing Harold Holcroft, possibly the most talented GWR designer.
So the NSWGR adopted the exterior features of GWR locomotives but without the knowledge of the design intent behind them.
The tapered boilers did not include the curved sides of the Belpaire fireboxes used by Churchward and his successors on the GWR which were derived from designs of the Brooks Locomotive works in the USA. These features were eventually adopted in the early 1950s for the 35 and 36 class replacement boilers.
In particular, the flanged driving wheels used in conjunction with knuckle jointed coupling rods did not work out. Holcroft had used much simpler spherical ends on normal rods on GWR locomotives.
Eventually, the 53 and 55 classes were rebuilt with flangeless second coupled and driving wheels and conventional coupling rods, becoming similar to the 50 class in that respect, apart from the longer wheelbase.
In 1937, a new design of standard boiler was fitted to a 53 class locomotive. This was externally similar to the original T class boiler but had the wider water legs (and slightly smaller grate area) of the tapered boiler. This boiler was called a "Standard Goods" boiler and was progressively applied across the fleet so that by the 1950s most locomotives had that type. Even a non-superheated version of the standard boiler was produced.
The term "Standard Goods" was used for all three classes once they had the same boilers, but strictly this did not apply to any locomotives before 1937, and never to the different types before 1924.
In fact, had the 1924 reclassification not taken place, the converted TF class locomotives with a standard boiler might have been relassified "T" since all the distinct features had been removed. Apart from the slightly longer wheelbase the locomotives were the same. The NSWGR diagrams never acknowledged the weight of modified 53 class locomotives as being lower (nor of 50 class locomotives with standard boilers as being slightly heavier).