For people who never saw the Classic stories while they were in their first or second run on PBS, I get that.Talking about The Doctor sacrificing himself, by the time I saw Androzani, I'd already seen the 9th and 10th Doctors sacrifice themselves for companions/friends, so it seemed like a normal thing for The Doctor to do.Well, it's a regeneration story, for starters. Those tend to be among the most remembered. And this was just a plain damn good story. The ending is especially poignant, as the Doctor sacrifices himself for his Companion (first time he ever did that), and we see that he still feels guilt for Adric's death.
It's also the only one on the list for which my opinion is among the popular choices.
But please keep in mind that for those of us who did see this in first/second run in the '80s, it was a new thing, and not what anyone expected.