SG-A 5th season was the start point for me to handle all the "new" Atlantis work. SG-1 was so much better in all aspects so I really couldnt start watching those when they were toe-to-toe. I felt like Atlantis was 2nd class show with 2nd class talent onboard.
All this changed when I watched Season 5 Episode 8, "Queen". Really felt that the acting was nice and clean, alliances come and go but this was convincing to me atleast.
Drama, action, plot, turn of twists. Thats how you do an great episode, just take a look at the SG-1 eps ;)