Goku and Vegeta start out as mortal enemies, but slowly their relationship blossoms into a brotherly bond, united by their Saiyan roots. Fatherhood blesses both young men and, each with two bundles of joy to look after, priorities have to be established, with the ultimatum boiling down to family, or fighting.With Saiyan blood urging both warriors towards combat, it seemed that the outcome would obviously lean towards violence, and child-rearing would inevitably be left to the women. However, only one Z-Fighter overcomes his baser urge to fight to be with his family, showing some of the most significant character development in Dragon Ball Z.
Goku & Gohan
Son Gohan is the golden child, having received the most attention, out of the two brothers, from Goku. However, this father-son relationship could be described as relatively toxic, as Gohan is constantly being pushed to follow in Goku's footsteps, regardless of his unmistakable aversion to combat. When viewers first meet Gohan, he shows no signs of the typical Saiyan bloodlust and is instead rather timid and easily frightened. Nevertheless, Goku just can't wait to get his son over to Kame House to begin his training, which Chi-Chi only allows after Gohan turns four.
During this time, Raditz arrives on Earth and kidnaps his nephew, so as to entice Goku into battle. The Saiyan hero valiantly lays down his life to save Gohan, but unfortunately leaves him fatherless in the process. Piccolo takes the young boy under his wing and the two quickly form a powerful bond as Gohan is taught the Nemekian ways by his new father figure. Even after Goku's return a year (and two days) later, Piccolo remains Gohan's ultimate role model, and his father seems to make little effort in reconnecting with him. Gohan could possibly hold some resentment towards Goku, for forcing him into the world of combat, which he so often tries to escape as the years go by.
Goku & Goten
Goku's second son, Goten, is already seven years old when he first lays eyes on his father, who had died before his birth during battle in the Cell Games Saga. Although his death was honorable, many fans wonder if Goku could have returned to his family from Planet Kai sooner. Goku planned on visiting Earth for just one day, and not even for his family's sake, but rather so that he could compete in the 25th World Martial Arts Tournament. Goku unashamedly did not even know that he had another son, as he ignorantly points Goten out as having an uncanny resemblance to himself. Goku adopted the "out of sight, out of mind" mentality while training, never once asking King Kai for updates regarding his family's health and happiness in a whole seven years!
As a young child, Goten receives no additional martial arts training, besides what his mother, Chi-Chi teaches him. Somehow, he still manages to reach Super Saiyan at age seven, even with such limited resources. Gohan only starts getting involved with his brother's training when he discovers that nobody had taught him to fly, and finally Goten receives some Saiyan wisdom. For his age, Goten is considered by many to be significantly stronger than young Gohan was and, with sufficient training and guidance, the lad could very likely be an unstoppable force today. Not to say that he is a weakling, but Goku really dropped the ball by helping Goten truly reach his full potential.
Vegeta & Trunks
Initially, Vegeta was not the best father figure to his firstborn, as he still prioritized fighting over family, comfortably driven by his Saiyan mentality. Vegeta's aloofness may have been due to the strained relationship he had with Bulma, as apparently conceiving a child together was not enough incentive to end their constant bickering. However, the pair bonded after the Cell Games and were eventually wed. His love for his family is put to the test when Majin-Boo strikes, and Vegeta risks it all (including his precious pride) to save Trunks and Bulma.
Trunks was well-loved as a child, but not spoilt, as Vegeta was tough on the boy when it came to his training. All the extra time working on combat skills, however, gave Trunks and Vegeta ample opportunities to bond, and the fearrsome warrior inevitably become a role model to the young Saiyan hybrid. For his entire life, Vegeta has been focused on gaining power and spreading his empire as the Saiyan Prince, but since finding fatherhood, he has sacrificed everything to help his son's development.
Vegeta & Bulla
The Saiyan Prince was so excited at the prospect of a baby daughter, that he already decided to the name Eschalot before her birth, to honor their Saiyan roots. Much to his dismay, Bulma interjected her motherly authority and baby Bulla joined their family instead, as the apple of her father's eye. Vegeta was offered the opportunity to participate in the Zeno Tournament (competitions, his favorite!) but this dedicated dad declined the invite in order to remain with his family. It is clear in the Baby Saga how well Bulla has Vegeta wrapped around her little finger, where the Saiyan is seen driving his daughter around town, the car practically overflowing from their recent shopping excursion. Quality time with the kids is evidently the main goal for this once combat-orientated villain.
And the Award Goes To...
Goku and Vegeta are two sides of the same coin when it comes to their passion for fighting, however, their priorities are wildly unbalanced. While both strive to become the strongest Saiyans and protect those they love, Vegeta is not willing to sacrifice the bond that he has with his children in order to achieve it. While it is still important for the Z-Fighters to be physically capable of protection, quality time is just as vital, and Goku has been mostly absent for both of his son's childhoods.
Fans cannot deny that both fathers have given their lives to save their loved ones. However, Vegeta also sacrificed opportunities to excel for the sake of his family, whereas Goku's focus seemed more concerned with the prospect of a new fight, with little thought seemingly given to those he left behind. If viewers were sent back to the first time they saw Goku and Vegeta side-by-side in Dragon Ball Z, they would have never guessed that Earth's greatest hero would become the one to earn the title of Dead Beat Dad.