I only check this forum once in a while and almost missed an epic thread. I'll suggest one for each of the 2 series.
Secret Origin. Just to hear what the "first" episode would sound like if it was a different cast.
-Black Jack Justice:
The Problem Of The Perplexing Pastiche. Yes, I know it's new but your gender ideas would make this episode even weirder. Jack sleep deprived thinking he's Sherlock Holmes walking in to see Trixie and their client.
Trixie: "Just between us men, are you drunk?"
-Others and close seconds:
The Dream Factory: Just to hear again the Flying Squirrel doing The Grimes for a second time.
Justice Delayed: This one is just special to me. Specially they failed at a case and still got a happy ending.
A Holiday Apology: Oh wait, never mind. It's not really an episode but I'm keeping it in my playlist.