The weakest part of Stargate SG-1 were,
The villains,I feel like when I watched this show My main complaint were the villains in this show.
You have the Ghoul a houled. They're just not likable...
Apophis not so memorable. in my opinion.
Anubis just the same kinda boring.
The ori just feels like a forced filler.
The REPLICATORS! Awesome for the first 5 or 6 seasons. Then the whole replicator plot-line went over to Stargate:Atlantis and is one of the main reason SG:A failed.
Way too many replicator plot-lines were just becoming less scary and little more silly.
The ancients were not villains but just a bunch of a-holes.
The wraith, fun in the first season of Atlantis, 2nd season okay. But the whole show? It became boring and lame.
The lucian alliance was a great part in SG:Universe and was awesome! Just my opinion.
I think the main problem this show had were the villains. Most of them were not memorable. Or they're just not likable. I never really felt mad or something. I loved the heroes but the villains were just kinda lame in this show. I'd say Scorpius in Farscape, or Gal Dukat in Deep Space Nine were tons better villains. They were tons more likable and epic on screen. Incredible acting too! It's unfortunate stargate didn't have the same villains.
Here are my 2 cents.