SG-1's prime is the last few episodes of season 1 to the end of season 6.
I always felt season six was the low point of the show, you have Jonas instead of Daniel, RDA is starting to phone it in and lose interest but hasnt made it as overt as he did in 7 and 8 yet, just a general mehness for me.
And personally, as good as the early to middle seasons are, the best season by far for me is season 10.





I thought Jonas was a great character addition, I was almost sorry to see Daniel return, and I say that as a big fan of the character and Shanks. I wish they'd found a way to retain both characters, at any rate.
Seasons 9 and 10 are, for the most part, diabolical. Mostly thanks to the oh-so-funny Vala bits.