Not every Hokage in Naruto is worthy of the title and capable of fulfilling their duties. In fact, some didn't even wish for the position to begin with, while a few were just unqualified.
However, every Hokage is chosen for a reason. Typically, they embody the Will of Fire, whether it be in their actions or ambitions. Protecting the village should always be the top priority for any leader, and that is also a factor that needs to be taken into consideration.
Shinobi usually receive the title if they are deemed the strongest in their village, since they have trained all their lives with the purpose of protecting it. One only has to embody the soul of the Leaf to be the Hokage. Social status is inconsequential.
Every Hokage in Naruto ranked by capability, including Tsunade
Hashirama united various Shinobi to form the Village Hidden in the Leaves. As the first Hokage, Hashirama worked tirelessly with Madara to create a peaceful environment. The world, at the time of his birth, was ruled by the division of clans, and he noticed how his friendship with Madara Uchiha was forbidden. So, he sought to destroy the older traditions and usher in the age of peace.
Hashirama personally trained the Third Hokage. His influence remained palpable even after his death.
Tobirama was quite the opposite of Hashirama in that he was much more straightforward. His pragmatic nature helped him shape the Leaf into what it was.
He noted that the Uchihas' Curse of Hatred hindered progress in the long run. So, he singled them out by forcing them to be the police force of Konoha. This decision led them to foster a deep resentment towards Konoha that would boil over in a few decades.
Minato was chosen as the Fourth Hokage due to his honesty and bravery. He was very well-loved in the village. When the Nine Tails was unleashed, Kushina and he sacrificed themselves in order to save the village. He performed the Reaper Death Seal that would ultimately devour his soul.
Tsunade, the granddaughter of Hashirama, was a powerful medical ninja that healed hundreds of Shinobi and earned the title of Sannin before becoming a Hokage.
In the role of the Hokage, she valiantly fought Madara Uchiha along with the other Kage. When they were too injured to fight, she held up quite well against the undead Uchiha.
The vessel for Kurama, Naruto Uzumaki suffered endlessly for several years. However, he never lost his determination to occupy the seat of the Hokage one day. After successfully becoming Lord Seventh, he raced towards the source of the problem and defended the village with his life when the Leaf was threatened by an alien race. His legacy is only just beginning.
Kakashi was never expected to become the sixth Hokage, yet he accepted the role after the Fourth Shinobi World War. He did an adequate job and led the village during a peaceful and stable era. Trained under Minato, Kakashi was already a prodigy. However, his prowess as a Shinobi reached legendary heights once Obito gave him his Sharingan.
Hiruzen, the Third Hokage, is regarded by many fans as a bad leader. Despite staying alive for a long time, he could not make as strong an impact as the rest.
His decision to not execute Orochimaru the moment his atrocities were exposed triggered his downfall. He tried to rectify his actions, but it cost him his soul. Hiruzen used the Reaper Death Seal on him during an intense fight, but was not strong enough to seal him completely. Hiruzen, as part of the contract, had to give up his life while only Orochimaru's arms were devoured.