Favourite Stargate Episodes

There's a thread for favourite Star Trek episodes so I figured I'd start one for Stargate too (for those that may be interested), seeing as SG1 is probably my favourite series of all time, Atlantis and Universe would rate high on my list also.

Some of my favourite episodes from SG1

"Window of Opportunity" from series 4, for obvious reasons, hilarious episode.
"Ethon" from series 9, a follow up to the episode "Icon" from series 8.
"Nemesis" series 3 finale, introduction of the Replicators, hinted at by Thor earlier on in series 3.
"Camelot" series 9 finale, the battle scene was excellent but the dread and excitement when the Ori fleet arrive through the Supergate was the high point, with Daniel quoting the book of origin before the battle ensues, always loved the score for the Ori too.
"The Fifth Race" really expanded the mythology of the series and loved the call back in the last ever episode when Thor is talking to Sam telling her "you are the fifth race", emotional.
"Death Knell" from series 7. Good tension, action, stakes, top quality episode.

I will also say SG1, Atlantis and Universe always killed it with series finales and premiers. So many excellent Cliffhangers that always seemed to pay off nicely every time.