I will respect the OP's wishes and return to the topic of the thread.
The way I view it, there are three main factors to consider:
1. Quality
2. Quantity
3. Success
I will be providing three candidates chronologically, explaining my reasons for each, and then select the one that I believe to be the best example of the Golden Age of the Sith.
First off is Vitiate's Sith Empire. This order possessed both great quality and quantity of Sith, effectively possessing vast numbers of Sith, with a fair amount of powerhouses in there, effectively upholding the first two criteria. Unfortunately they kinda drop the ball on the third one relative to my other two candidates, which was success, seeing as Vitiate's empire never controlled the Galaxy.
Next up is the Banite Sith. Bane's Order possessed some of the most powerful Sith in Galactic History, "thirty in a millennium rather than the tens of thousands fit to be Jedi." The Banite Sith achieved such great power through the training and ambition of one day becoming the Dark Lord. This great power and secrecy culminated in the Grand Plan's fruition, and the Sith successfully taking over the Galaxy. At the expense of the criteria of quality and success however, the Banite Sith lacked the second criteria, which was quantity, with only two true Sith at a time, and only thirty Sith in a millennia.
My third and final candidate is Darth Krayt's One Sith Order. This order of Sith possessed great quantity with legions of Sith, and great success with their successful takeover of the Galaxy. Unfortunately they drop the ball on the first criteria, which is quality. The One Sith philosophy of fanatical devotion to Krayt to the point of suicide on his whim led to a general lack of ambition in his order, which is a crucial part in growth of a Sith's power. Only two or three of them ever aspired to be anything greater than Krayt's servants, and this shows when you see hordes of One Sith treated as fodder.
So the conclusion I have come to from my three top candidates is that there is no ideal representation of all three criteria, and the best we can settle for is one that upholds two of them the best. I will now go about determining that.
As per quality, this one falls between the Banite Sith and Vitiate's Empire. Bane's order I feel really outclassed every other order in this respect, with every Sith in the order training with the ambition to one day become the Dark Lord of the Sith. The Banite Sith trained with greater raw power, as a result of immense elitism in the selection of apprentices, greater ambition than any other order, with the prospect of one day becoming the Dark Lord, and immense knowledge with all the Sith knowledge of the order pooled together and added to for a thousand years. Quality: Banite Sith
As per quantity, this one falls between Vitiate's Empire, and the One Sith. Krayt's order had legions of Sith, however Vitiate's Empire had flourished and grown for much longer before revealing themselves to the Galaxy, and had a **** ton of them as per SWTOR. Quantity: Vitiate's Empire.
As per success, this one falls between the Banite Sith and the One Sith. Both took over the Galaxy, but I'd have to credit the Banite Sith for holding Galactic control for over three times as long as Krayt's One Sith. I'd also credit the Jedi purge of the Banite Sith being more successful, taking out 99% of a much larger order than the around 50% of the Jedi Order of Krayt's time. Success: Banite Sith.
Overall, based on relative superiority in factors compared to each other, I have determined that the fruition of the Banite Sith's Grand Plan is the golden age of the Sith, at least from my point of view. This would be followed closely behind by Vitiate's Empire and then Krayt's order.