9. Season 2
Season 2 started off quite well, concluding Season 1's cliff-hanger well and then introducing us straight away to a new player in the galaxy, the Tok'ra, as well as a closer look at the enigmatic Asgard. Unfortunately after the introduction of somewhat game-changing potential allies as these, the series struggled to make the Goa'uld continue to be a threat for a while. The introduction of a potential new enemy, the Re'tu, was a complete misfire, as was the possibility of returning villian Linea.
Nevertheless, the season still had great episodes in there. The very second episode of the series, In The Line Of Duty (not to be confused with a certain highly addictive cop show) shows us the Ashrahk assassin, a villain type that was woefully underused. Touchstone shows us our first glimpse of the rogue NID, which would eventually become The Trust. The best episode of the series is probably Need, where we are allowed to examine the effects of the Goa'uld Sarcophagus outside of the regular context.
So, all in all, a decent season that didn't quite offer as much as it could, especially seeing as how its last episode was a glorified clip show.