The whole Cell Saga (the whole Future Trunks thing, not just the Androids) is as a whole, my favourite part of the series and there's a few reasons for that. Yoshioka already mentioned one of those, I'm just generally more drawn to the sci-fi elements featured there, with the Androids and time travel and everything. It's pretty much the only part in all of Dragon Ball that really leans into that, so it's a plus for me. Similarly, Cell's introduction is like the only time the series delves into horror, and that certainly left on a young me.
But the most important reason is I think it's the period of the series where the whole cast is treated the best. Admittedly, it's not Vegeta's best character arc in the series (honestly from Z, it's his worst [unless you count Saiyan where he doesn't really have one) but he does have his own story arc and his relationship with Trunks is pretty interesting. Especially the inverse parallels with Goku and Gohan's relationship. Future Trunks himself was a pretty cool and likable character. Piccolo has his own story arc, his decision to fuse with Kami was treated with weight and he gets an awesome fight with 17. Which reminds me, Androids 16-18 are some of my favourite antagonists in the series. They're pretty likable, and not particularly villainous. They never really do anything bad, they even avoid killing people when they easily could've, they're just a threat because they want to fight Goku since it sounds like fun. And 17 treating it like a game was always entertaining, especially when 18 grumbled about it. Speaking of 18, Krillin got his own character arc of having a crush on her. Tien got his best and most hype moment in the entire series stalling Cell, and we finally got the payoff of all the build to Gohan's power with him defeating Cell.
Which is noteworthy for two reasons. I. The Cell fight has the best climax in all of Dragon Ball, the father-son Kamehameha defeating Cell after an errant ki blast from Vegeta. Made especially delicious with how dramatically tense Cell's return was, and Vegeta finally fighting for someone else after a series and especially arc where he only fought to prove himself superior. II. Goku didn't save the day, Gohan did. The Cell Saga diverges the most from Dragon Ball's, Goku saves the day formula, which I really appreciate.
I know some of this isn't much, like Krillin's little subplot isn't anything to write home about and Tien's moment ultimately accomplishes nothing, but I just love the amount of different characters that have something going on or some highlight moment. Goku, Vegeta, Gohan, Krillin, Future Trunks, Piccolo, Kami, Bulma (removing 16's bomb, dropping exposition about Gero), and Tien all get worthwhile stuff to contribute to here. And the ending resolution is the best in Dragon Ball.
