Best Threat Of Its Day: the Next-Generation episode/s that introduced the Borg.
Best of Deep Space Nine: The back-story about Capt. Sisko, his son (Jake?) and his ex-wife; 'Little Green Men', where Ferengis wind up on our 20th-century Earth and start bargaining; and (sorry---I don't know the title) O'Brien, I believe, asks Worf if the goateed mesh-clad misfits on Kirk's Enterprise (using footage from 'The Trouble with Tribbles') are Klingons; Worf's response: "We Do Not Discuss It!"
Worst of Deep Space Nine: That whole last-season (or longer) story arc about the High Priestess, or whatever she was, causing $#!+ for everyone.
Andromeda: The most formidable thing Sorbo had to fight was the urge to hook up with Lexa Doig (well, the Magog were kind of nasty.....)
Voyager: The 'Left on Our Own' thing worked, but it had before and has since; lots of two-parters /cliffhangers were well done, including a three-story arc--not consecutive--about Captain Braxton and his Timeship (he was stranded on Earth for something like thirty years---without any of his 29th-century comforts---and rescued eventually by Voyager and Janeway, whom he held responsible. And don't forget the future Janeway who came back to sacrifice herself and end the Borg by checkmating the Queen.
Most Offended Enemy: Species 8472, who was here only because of a rift the Borg opened between our universe and their Fluid Space. How about their use of DNA splicing to lose their third leg and impersonate us---with Ray Walston (My Favorite Martian) playing the duplicate of Janeway's old instructor.....cute.
Enterprise (the prequel with Scott Bakula and Jolene Blaylock): a first-season ep titled 'Carbon Creek' in which three of the crew are on 1957 Earth for a while and try to fit in--amusing in a series that otherwise failed to impress.
Stargate DS1 (Did you mean 'SG'-1?): Amanda Tapping held my attention even in the few eps that otherwise did not; any show that ran for ten years could have run for another ten, if people didn't want to go home and count their money.
Stargate Atlantis: Good premise and an interesting enemy---at least at the outset---and Jason Momoa's Wraith-hunter was a lot of fun. From Season 4's 'Midway':
Ronon: "You sure say 'indeed' a lot."
Teal'c: "Indeed."
Stargate Universe (cancelled after two seasons): Dark and slow, unless you're a FAN (did someone say, 'Geek?') which I am.
I guess that's enough for now.