History’s 6 Greatest Armies

There are always lists - everyone has different lists - and yet there is always a good read in looking at another's list and why they thought such. This one.. left out a few and added some maybe that would not have included. When one looks at Greatest Armies - usually they are lead by a Great Captain... not just a standing force. So the first question of mine would be - where is Macedonia? Next - where is the Spanish Army - who were the power in their day and around for centuries? The Germans/Soviets/US were all great - but for how long in duration and over how many wars? Where is the Vikings at for this list? And where were the Byzantines? How about the Mughals?
If one wants to look at greatest... that is but a perception of time in history. But one can always build a list towards defining it..