SeleucusNicator
Diadoch
The two armies I immediately think of when I think of dominant armies are Napoleon's army and the Prussian forces during the time of Bismarck and Moltke Sr.
In both instances, somebody took advantage of a new development (nationalism in the case of Napoleon; railroads and fancier guns in the case of the Prussians) and combined it with appropriate new tactics to go on a rampage. Bismarck knew when to stop; if Napoleon did, who knows how long his empire could have lasted.
I think that a lot of "superior" armies are good simply because they are the outlier; they have a new advanatage that others don't and know how to use it (or perhaps have an advantage that others have, but that only they know how to use. Look at the Germans in WW2 and tanks, for instance). The problem, of course, is that other powers will quickly immitate you, making your advantage nullified. You must act quickly.
In both instances, somebody took advantage of a new development (nationalism in the case of Napoleon; railroads and fancier guns in the case of the Prussians) and combined it with appropriate new tactics to go on a rampage. Bismarck knew when to stop; if Napoleon did, who knows how long his empire could have lasted.
I think that a lot of "superior" armies are good simply because they are the outlier; they have a new advanatage that others don't and know how to use it (or perhaps have an advantage that others have, but that only they know how to use. Look at the Germans in WW2 and tanks, for instance). The problem, of course, is that other powers will quickly immitate you, making your advantage nullified. You must act quickly.