Louie
Best: the episode where he sleeps with Joan Rivers
Worst: the episode where he goes to Afghanistan and a baby duck unites the world, just the most maudlin, hackneyed crap, worse than the hoakiest of late season MASH episodes.
Big Bang Theory
(too lazy to look up titles)
Best: The first Wil Wheaton episode (“No… not Enchanted Bunny!”)
Worst: The season opener where they had been in the (Ant)arctic for the last 3 months, and the heat had gone out a few times…
I’ll provide the corollary:
I honestly can’t think of a most favorite episode, as I love almost all of them, but a real stinker was the one where the gang has to distract Tom Skerritt(?) from finding out about a dead person (or something like that) so Norm ends up carrying him around the yard on his shoulders all night. This was like a really, *really *bad episode of Laverne & Shirley.
The Andy Griffith Show
Best: Opie’s Charity
Worst: Almost any of the color episodes (although I refuse to believe they really exist).
Futurama
Best: Luck of the Fryrish. The end had me in tears.
Worst: A Pharaoh to Remember. Bender being a jerk for 20 minutes and everyone paying for it. But hey, the planet looks like ancient Egypt! So that makes it funny!
Simpsons
Best: Homer at the Bat. Brilliantly executed comedy. Mr Burns steals the show in so many ways.
Worst: Kill the Alligator and Run. One of the few episodes I’ve never re-watched.
South Park
Best: Starvin’ Marvin. How can you not love bringing an impoverished third-worlder to a buffet and telling him, “These are appetizers - you eat them first to make sure you’re hungry enough for the main course”?
Worst: A Million Little Fibers. Oprah’s private parts speaking? CRINGE.
Night Court
Best: Mac’s Dilemma. The dead Japanese businessman who gets lost in his motorized wheelchair is the funniest subplot ever.
Worst: Harry’s 15 Minutes. No one comes off looking very good in that one.
The Dick Van Dyke Show
Best: It May Look Like a Walnut: Under the influence of science fiction, Rob fears that a walnut will steal his imagination and his thumbs. Danny Thomas guest-stars. (Wiki episode synopsis)
Worst: Boy #1, Boy #2: Laura and Millie become unbearable stage mothers when their sons are cast in a television commercial (in other words, Richie REALLY can’t act)
There’s a scene in this one where Mary Tyler Moore slides out of a closet down a mountain of walnuts. She’s face down and wearing those stirrup pants. It made me feel all funny in my boy parts.
IMHO, there are no bad episodes of Firefly, but:
Best: “Out of Gas”–we learn how the crew came together.
Worst: “Safe”–stereotypical dumb hicks try to burn River as a witch.
Couple more:
It’s Always Sunny in Philadelphia
Best: Who got Dee Pregnant? : A great Rashomon-style story that is flat-out hilarious. Dee as an actual ostrich is what puts it over the top.
Worst: Charlie Wants an Abortion.
Venture Brothers
Best: Operation P.R.O.M.
Worst: Careers in Science.
New Doctor Who
Best: The Waters of Mars - The Doctor, in a fragile state of mind, is forced to decide between saving the life of a woman he idolizes, or keeping the web of time intact.
Worst: Invasion of London - London is invaded by farting aliens wearing human fat suits.
**Classic Doctor Who ** (I’ve only seen Doctors Five through Eight)
Best: The Caves of Androzani - The Doctor becomes entangled in a conflict between illegal weapons dealers and a crazed man holding a world’s supply of vital chemicals hostage, all while trying to save himself and his companion from a deadly illness.
Worst: Attack of the Cybermen - …? I assume something happened in this, but damned if I know what. I feel confident that sniffing glue for 90 minutes would kill fewer brain cells than this episode.
The Simpsons
Best: Homer in Space - I, for one, welcome our ant overlords.
Worst: Sadlesore Galactica - Brain eating elf jockeys threaten Homer and Lisa’s racing/diving/football playing horse.
Futurama
Best: Parasites Lost - Fry gets a helpful case of worms. Touching, gross, hilarious. The epitome of good Futurama.
Mystery Science Theater 3000
Best: Track of the Moon Beast. An underrated classic.
Worst: The bad ones are hard to even recall, but I remember being unendingly bored by The Mad Monster.
Farscape
Best: Crackers Don’t Matter (Crew grows murderously paranoid with their obsession over food cubes)
Worst: Taking the Stone (Chiana discovers her brother dies and flees to a graveyard planet full of stoners)
You liked the “John Smith” eps?? Umm, okay… 
And you clearly got these round the wrong way 
I’m no Gaiman fangirl, but I lovedthe Helena Bonham-Carter style Tardis
Buffy
Best - Hush (obviously)
Worst - Where the Wild Things Are
Angel
Best - I Will Remember You
Worst - something with possessed Cordy getting it on with whiny-teen-brat-boy Connor.
Arrested Development
Best: Pier Pressure. The lies keep piling on when Buster needs George-Michael to buy him some weed.
Worst: Ready, Aim, Marry Me. Martin Short guest stars as the unfunny cripple Uncle Jack, while Tobias experiments with body chocolate.
The Dick Van Dyke Show
Best: “The Curious Thing About Women”
Laura opens and reads Rob’s mail, she giving him a Reader’s Digest version of it, and even throwing away what she considers unimportant. MTM said she liked this one because it let her be the nut instead of the rational one. I like it because it works out at the end EXACTLY the way Rob’s comedy sketch ended, with Laura’s horror that she did exactly that, and the Helper’s hysterical reaction.
Worst: “The Boarder Incident”
Buddy stays with Rob and Laura for a few days and he is not the best house guest. This episode is just uncomfortable.
South Park
Best: Scott Tenorman: Cartman gets the ultimate revenge on a older kid.
Worse: Insheeption: An terribly unfunny inception parody.
MyLittlePony:FIM
Best: Suited for Success: Excellent musical numbers, great humour and a story we all can relate to.
Worse: “A dog and pony show”: Extremelllly annoying, I wanted to take the episode’s lead character to a glue factory.
Simpsons:
Best: You only move twice: watch it and you’ll understand
Worse: When you dish upon a star: It was the episode that cemented the use of lazy celebrity cameos on the show.
You didn’t like them? I thought they were great, too. But I do agree that “crazy TARDIS woman” was awesome.
Since I’m talking about them,I’ll throw out my own picks:
Doctor Who (9th Doctor)
Best: “The Empty Child”/“The Doctor Dances”
Worst: “Aliens of London”/“World War III”
Doctor Who (10th Doctor)
Best: “Blink”
Worst: Ooh, tough call…“The End of Time” was just all over the place and stupid, but it’s hard to put into words how much I despise “Fear Her.”
Doctor Who (11th Doctor)
Best: “The Impossible Astronaut”/“Day of the Moon”
Worst: “Night Terrors”
Buffy
Best - it’s hard to argue against Hush, but I have to pick The Body.
Worst - Sorry, as much as I was grossed out by the Riley/Buffy sex-a-thon (hate Riley), it also featured one of my favourite scenes when the gang comes across Giles singing in the cafe swoon. That alone redeems this episode.
The true Worse **Buffy **Episode ever: Anne
As for Angel - I don’t know about worst, but I agree the above is the best. I can still get choked up thinking about it and I hated Angel & Buffy together!
But the Doctor’s Wife had my favorite exhange of the entire series.
Amy: The TARDIS is a woman?
The Doctor: Yes.
Amy: Did you wish really, really hard?
Firefly
Best: Serenity
Worst: Everything else
Doctor Who
Best: Genesis of the Daleks - Difficult to chose one, but this a great lazy choice 
Worst: Revenge of the Cybermen - The series took a nose dive with Colin Baker, but ROTC has lots of wandering around in caves, in circles, repeatedly, going nowhere.
New Who
Best:
Worst: Agree with
Better yet, my daughter is a recent Whovian convert and spotted that in my DVDs :smack:
Star Trek
Best: Amok Time - It’s got the big three being pals, which was the best thing about the show (amongst all the other great stuff)
Worst: Turnabout Intruder - poor send off for the show, poor send up of women
Star Trek TNG
Best: All Good Things - I guess you need to have seen the rest of the show to appreciate it, but a great send off for the show and the crew
Worst: Shades of Gray - I hate clip shows at the best of times, but on my favourite show? And it’s a telepathic clip show too :mad:
From Numb3rs:
Best: Uncertainty Principle
Worst: Thirteen