These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Raiker from season 1's "Space Fall" is a sadomasochistic dictator to the prisoners. He keeps a keen eye on female convicts who can pass muster to be his sex slaves, who get dumped out of the ship when they reach the prison planet or en route. When our protagonist Blake takes over the ship, Raiker deals with this by executing the prisoners to get Blake to surrender, and then two more For the Evulz. He appalls even his fellow crewmates.
Crowning Moment Of Awesome - Star One. An extragalactic invasion fleet is on its way into the Galaxy and the only defence the Federation has is at least 15 minutes away. Avon moves the Liberator into the firing line and is told, "This is crazy"; he sneers back, "When has that ever stopped us?" the music mounts and then "FIRE!" straight into the end theme music.
To quote Martin Odoni, you know you've watched too much Blake's 7 when "you dismiss the works of Tchaikovsky, Mozart and Brahms as amateurish because they don't have as many major chords as forty seconds of Dudley Simpson". note The composer of the signature music.
Foe Yay - Between Avon and Servalan, who share a few dysfunctional moments during the third season. In "Death-Watch," it's hard to tell whether Avon is trying to manipulate her or just contriving an elaborate excuse for a hug.
Also, Servalan and Tarrant in "Sand".
Avon: You believed her? Tarrant: Not necessarily. I think it was a gambit to gain my sympathy... in a nervous situation. Avon: And she got it too, didn't she? Your sympathy I mean?
Fridge Horror: Blake was sent to Cygnus Alpha on the charge of molesting kids, kids who the Federation implanted Fake Memories in of the events who you realise will be living with those Fake Memories for the rest of their lives.
Ho Yay Shipping - Generations of fans have read subtext into Blake and Avon.
"Death is something [Blake] and I have faced on a number of occasions; I always thought his death and mine might be linked in some way."
Magnificent Bastard: Blake to an extent (being able to rope the reluctant into his scheme to destroy the Federation), Avon in spades...but anything they were able to do, Servalan did it better and in stiletto heels. The fact she outlives them both pretty much cements it. It's almost a shame Avon turned down her offer to rule together.
Moral Event Horizon - Avon, in one of the last episodes, "Orbit". Avon and Vila have tricked a Mad Scientist out of a powerful new weapon with a fake Orac only to find that he's somehow weighed down their shuttle so it can't achieve escape velocity. Our heros are busy stripping everything out of the shuttle to lose weight (including the powerful new weapon), when Orac announces they only need to lose 70 more kilos. When asked by Avon (who believes Vila is out of earshot) what weighs 70 kilos, Orac tells him that "Vila weighs 73 kilos". Avon gets his gun and goes looking for Vila (who's gone into hiding!). Avon then finds the 'speck of Neutron Material' embedded in perspex that is really weighing down the shuttle, but can't persuade Vila to help him push it out of the ship because Vila thinks Avon is still trying to kill him. He manages to do it by himself, manfully. Opinion is divided on whether Avon would have actually killed Vila if it had come to it.
The Scrappy - Del Tarrant in the third and fourth seasons.
Seinfeld Is Unfunny - The "fugitives running from a corrupt empire" premise has long since been harvested to death to the point where it'd be a unique subversion now to show things the other way around.
Also, the "futuristic" bases the Seven visit tend to look a lot like 20th century British oil refineries or nuclear power plants.
The final season had generally respectable effects for the time, thanks to advances in technology. The only real failure came from the very obvious matte lines in spaceship shots.
Tearjerker The final episode where most, if not all, of the characters are killed and "Orbit" where Avon and Vila can't gain escape velocity in their shuttle at the current weight, so Avon tries to kill Vila, who happens to match the weight. While Avon's looking for the hiding Vila, you can see tears on Vila's cheeks, from a deleted scene where he was crying.
The final fate of Avon's beloved Anna in "Rumours of Death": she was a high-ranking Federation Security agent assigned to watch him, and Avon kills her when she pulls a gun on him. As she dies, she whispers, "It wasn't all lies, my love."
The Zen's death and final words.
Zen: "I AM SORRY. I HAVE FAILED YOU."
Villain Sue: Jarvik from "The Harvest of Kairos". Fills Servalan with submissive lust despite being a creepy Medallion Man, alleged tactical genius, has Tarrant mourning him as a Noble Demon even though he was an utter scumbag... Ick.