Wow, great question - hard to pick just one. But out of my top three faves (Death Penalty: Final Appeal, Daniela or Best Friends), #1 has got to be Daniela because of the awesome '70s music I came of age listening to

My favorite episode is Sandhogs, Season 4 episode 3. Coal miner killed by his brother in law.
Other top favorites are:
Best Friends
Sleepover
Into the Blue/The Long Blue Line

Yes, the spoiler
where they killed the poor guy, broke my heart.

The promise. I loved the way that the dude had his best friend's back even after her death.
Death penalty final appeal-
Holy crap, I did not expect them to kill him.
A time to kill and wishing- two other heart breaking episodes.
Finally who's your daddy. I liked Booker's relationship with the girl.

1. death penalty final appeal 2) slipping 3)torn 4)the hen house 5) Rampage 6)The sleepover

There are some I can't remember the titles of. For instance: 1. The one in which an innocent man was executed. So sad! Made me really angry. 2. The one about the woman who was murdered by her own husband, though everyone thought it was suicide (she was hearing "strange sounds" and so on). I am sure that storyline was inspired by Sylvia Plath's suicide. What if Ted Hughes had actually murdered her? And so on 3. The one in which the victim was a suffragette who was killed by accident, back in 1919. This case was the eldest in the whole series. Or am I wrong? 4. The one about an ambitious female journalist who, just after World War 2, met a man who had stolen the identity of a man who was killed in a consentration camp. They fell in love, but she (of course) discovered the horrible truth about
him. This was a very sad and intense episode, on many levels. 5. The one in which two teenage boys massacred a lot of people in a shopping mall, before both of them committed suicide. This took place in 1995. 6. An episode with a story from 1991 (I think), about a girl who was bullied by some other girls because she was a "nerd" and who was found dead in a hole in the woods. She had discovered that the leader of the bullies and her brother, were physically and mentally abused by their parents. Some episodes I remember the titles of: Fireflies, That Woman, Spiders, Debut.

I love most episodes. I haven't watched many since it ended, but off the top of my head, Justice, Revenge and The Sleepover were great. I feel I am missing some really good ones though.