Since I actually have more of a calm, level-headed voice in this issue, I'll go ahead and weigh in an unbiased opinion...
Zipp's original addon for IC2 allows for rapid productivity with keeping up with the ramp time of Induction furnaces. As such, it allows the machines to compete with the refining process of smelting ore and validates a reason to have a MV power grid running your machines. However, the balance issues remain with the original machines for the fact that the machines (literally) could grind tons of ore, resin, and not have to worry about the increased power load to a particular degree. The 1 EU/t for each machine can easily be negated with a renewable energy grid that can constantly feed power to the machine's ramp time. Yet the increased processing speed is the only feature that these machines come with (beyond MV tolerance, but that's a different issue)...
Atomic's machines start with a low, yet upgradable, ramp up that consumes more energy for the use of basic functions that many with zipp's addon took for granted. This is part of the reason why the changes angered so many, because now they had to manage around the more constant demand for power to keep the same (if not less) ramp up speed than the other machines. But despite this, the most attractive feature about Atomic's machines is due to the increased utility in the Macerator (and hopefully, eventually in the Compressor and Extractor machines). The ability to create bronze and refined Iron at dust form is a nice QoL adjustment from the machines so you don't have the hassle of running to a crafting menu just to make some dust, or have to double input in the Induction Furnace just to refine Iron. This change helps save time with ore processing for specific tasks, and allows a more flexible level of control for how you want to manage your resources...
So tl;dr
Zipp's Machines are for low ramp cost, low utility
Atomic's Machines are for high ramp cost, high utility
Take your pick...