Which is the most interesting battle in Dragon Ball Z?
Goku vs. Vegeta
I need to open this answer by saying that nearly every single significant fight in the original Dragonball was superior to nearly every single fight in Dragonball Z. In Dragonball, characters needed to innovate clever solutions to win their fights. Krillin forced Chiaotzu to do math to win his fight. Krillin pulled out Bulma’s boobs to make Master Roshi spew blood on the invisible man to help Yamcha win that fight. Master Roshi blew up the moon to turn Goku back to normal in their fight. Name a single moment in Dragonball Z when such unpredictable methods were used. There aren’t any. The closest we get is Krillin using a solar flare to get away from Dodoria. On top of this, since the characters in Dragonball were generally developed better, we were almost always more emotionally invested in those fights. As much as “THEN THE WHOLE UNIVERSE IS GOING TO DIE” might sound like high stakes, we’re frankly not as emotionally invested in “the whole universe” as we are in a fight between Tien and his former master, General Tao.
But if we only have Dragonball Z to choose from, then Goku vs. Vegeta wins easily. While DBZ is notorious for solving all problems by increasing brute strength, Goku vs. Vegeta is the only battle in the series where the characters (including the villain) do so through clever means.
At the start, Vegeta is immensely stronger than Goku. While Goku puts up a fight for a little while, it’s clear he stands no chance. In order to even the odds, he must use a technique that constantly hurts him and might kill him in order to match Vegeta at all. For the entire fight, we see Goku growing increasingly desperate.
Eventually, Goku starts to win, and Vegeta must find a way to overcome his foe. At first, he tries to blow up the planet, and fails. Then, he sacrifices a great deal of his energy in order to create a fake moon to transform. Vegeta turns into a great ape, dectupling his strength. Goku once again stands no chance.
To give himself a chance, Goku attempts another risky move. He starts to create a spirit bomb. Will this be what beats Vegeta? Nope! Goku is caught and fails!! We’re kept guessing. Neither character has a clear upper hand for reasons that are different from brute strength. Goku is crushed and left completely unable to fight.
At this point, the other characters get involved. Even better, they’re useful! This will never happen again. Every time other characters get involved from this point forward they serve as nothing but punching bags to buy time. Gohan and Krillin make a daring plan to cut off Vegeta’s tail, but they fail. Unexpectedly, Yajirobe, a character the audience has all but dismissed, sneaks out of nowhere and cuts the tail off himself. The good guys are back in the game, or are they?
While Gohan is fighting Vegeta, and losing, Goku gives Krillin the spirit bomb. Krillin throws the bomb at Vegeta, and misses, hurling it at Gohan. Gohan’s pure heartedness, a quality that is not brute strength, saves him, letting the bomb bounce off him and hit Vegeta after all. Vegeta is crippled and must retreat.
No other battle in Dragonball Z has anything close to this level of tension. Hell, this would be an interesting fight in a book! Every other battle can be summed up as “Hero gets beat up. Hero gets pissed and transforms. Hero defeats enemy with overwhelming attack.” The battle with Kid Buu departs from the formula a bit, but it doesn’t hold a candle to this.
It’s a shame that when Goku became an adult the battles lost the creative charm they had in the earlier series. Hopefully they’ll get some of it back in Super