When it comes to Dragon Ball Z discussion, the main story arcs -- Saiyan, Frieza, Cell, Buu -- rightly receive the most love and debate among fans. In contrast, the Namek, Android and World Tournament arcs are generally considered mere set-up at best or slow-moving filler at worst, rarely receiving much love in their own right. The Android Saga in particular is highly underrated. It features plenty of key moments, introducing characters who would grow into prominent cast members throughout Z and Dragon Ball Super while raising fascinating questions about what it means to be human.
The Spotlight Shifts From Goku
One of the Android Saga's key developments is Vegeta's debut as a Super Saiyan in the battle against Android 19. Having endured years of intensive, often life-threatening training in an effort to reach Goku's heights, he finally hits a moment when he no longer cares. As with Goku in the wake of Krillin's death, something subconsciously snaps in Vegeta's mind and he finally transforms. Ever the showman, he keeps it a secret and waits until Goku becomes fully sidelined by the heart virus before reemerging on the scene and obliterating Android 19. Though it's impossible to know for sure, it was widely speculated that Vegeta was the stronger of the two Saiyans at this time.
With Goku MIA for a long while due to the heart virus, the likes of Vegeta, Piccolo, Trunks and the rotating cast of androids are refreshingly given more time in the spotlight. Goku generally dictates and delegates many of the Z fighters' strategic moves, but here the others decide themsleves how best to deal with Dr. Gero's laboratory and Androids 16, 17 and 18. Normally when Goku goes missing for long periods, it's because he's training on another world to get stronger for an inevitable titanic battle. This time, however, he's stuck at home and powerless to do anything, leaving no choice but to put faith in his comrades to keep the world safe -- or at least prevent total destruction.
Android 18 Brings the Girl Power
In an extremely male-dominated environment, Android 18 wiping the floor with Vegeta was a pretty big deal. After repeatedly taunting her as being nothing but a tin-filled machine, Vegeta gets a brutal lesson in not underestimating your opponent for being different. Along with her strength and fighting ability, 18 also shows her interest in fashion when visiting a clothing store -- and Chi Chi's closet later on! The saga is a great introduction for a female character who can mix it with the world's strongest fighters while also embracing her femininity.
After his defeat, Vegeta's arrogance fades as he ventures off on his own to reflect on the battle. For how abrasive he tends to be in general -- remember the infamous "servant woman" comments toward Bulma? -- it's impressive that Vegeta isn't upset about losing to a woman android. Instead, he's purely disappointed at his own shortcomings in losing to a more powerful fighter. For all the significant moments in Vegeta's character development, this one tends to fly under the radar, but is an important step on his journey to becoming a good husband and father.
Blurring the Lines Between Good, Evil and Human
Although Dr. Gero is your standard sociopathic doctor and Android 19 is a fully obedient machine, Androids 16, 17 and 18 are far more complex characters. Brother and sister 17 and 18 are revealed to be humans who were abducted and modified into androids by Dr. Gero, explaining their more rebellious streak. Though they are treated as irredeemably evil by most of the other Z fighters save for Krillin, 17 and 18 only ever fight when they are antagonized into doing so, first by Vegeta and then later by Piccolo and Cell.
Due to his programming, Android 16 only desires to fight Goku and otherwise doesn't fight at all -- until he makes the independent choice to fight Cell and protect his friends. Unlike previous antagonists, Androids 16, 17 and 18 display empathy and look out for each other. 17 only fought the Z fighters after Trunks broke their agreement to stay out of Vegeta and 18's fight, while 16 fights Cell for the purpose of saving 17 and 18's lives. Although the debate doesn't happen on-screen -- outside of Krillin's internal struggle on whether to save 18 or blow her up -- this story begs the question: where is the line between good and evil, hero and villain or human and android? Providing complicated, ambiguous answers makes the Android Saga such an important arc in the series.