The case differences are pretty significant and shouldn't be dismissed easily imo. This is what I know about the case differences.
LZGH is going to be part aluminum and part stainless steel, which adds on the weight to the whole keyboard. The back bar is designs to provide two options for the incline angle. There two layouts available, 84 and 86, and each one has a different top case.
KMAC 1.2 has a full aluminum case and is hard anodized (some people reported that with constant contact with the case, the color from the original KMAC and KMAC LE changes, hard anodizing prevents that). The layouts available are also 84 and 86, but there is a block you can install for the winkeys instead of integrating it into the top part of the case. The feet for the case are different and you can also adjust the incline angle.
KMAC 2 (I believe) is also full aluminum and hard anodized. Layouts are the same as 1.2. But the bottom case is different. The feet are integrated into the case and there are holes where you can install small stands to further support the plate+pcb.