Not just because it holds up as some of the best the show has ever been, but for the nostalgia of the setting. The "modern day" earth episodes were so of their time AT the time that they are perfect little time capsules, it so precisely captured how it looked, how it sounded, how it FELT to live in the UK 20 years ago. All those people who saw aliens crash into big ben, they didnt have twitter to talk about it on, they invited their friends and neighbours round to watch the news about it together... these two seasons make me feel a really true and deep nostalgia like nothing else.
Also too many people skip christopher eccleston, stop doing that