Part of the draw of SG1 is there's lots of cool moments, but there's no ONE "moment".
It's just a consistent string of mostly retcon-free development over time. So you can, if you're paying attention, draw clear lines between disparate events in the series.
Also, the moustace-twirling villainy was part of what endeared me to the villains.
The fact that they WERE so hammy, after centuries. But weren't REALLY cognizant about how stereotypically evil they were.
Meanwhile, Jack & Crew are looking at these guys with cocked eyebrows going "Is he SERIOUS?"