I watched Sinners awhile ago and plan to rewatch + enter it into my media journal and maybe I'll expand on this idea in there but:
I would never hesitate to take the dark gift. I would not second guess my choice for one moment. I found that even in the framing in which vampirism allows you to remain living with a sibling a twin nonetheless! people would still refuse the gift. I'm in awe of that because I really don't understand it. I guess maybe the whole "life has no value if death doesn't exist" is a huge motivation for people and I agree with that notion but in some sense I think two things:
1. I, personally, would have to plot the downfall of money as an idea in society and the global world. I would spend my life dedicated to the downfall of capitalism.
2. surviving the passage of time makes you a living artifact + the removal of death gifts vampires the ability to entirely eliminate sources of human suffering. a visual novel I like that kinda touches on this is Cabernet. I believe they are in the mid 1800s in this game. you study under a doctor who discusses this notion at length. since vampires don't die they are allotted longer studies on human diseases and are able to advance science and technology faster than humans. this is why the downfall of capitalism would be my top priority. there is another vampire in this game, Arban, who bleeds revolutionaries. she discussing this idea too, I can't recall what she says exactly but the gist is basically: the more things change, the more they stay the same. because humans have such short life spans, the ways we challenge systemic inequality is immediate. think desegregation and the ada. this isn't to say these things are bad but they merely provided short term relief to issues that are incredibly deep.
in our current world I feel this is magnified by the existence of the Internet. the manosphere, Asians appropriating black culture, porn and it's extremity with a.i. the Internet has allowed these issues to compound and speed up excessively because the Internet is peer to peer connection and, funnily enough, it always reaffirms the things a person already believes about themselves, the world and others.
so yea basically vampirism has all the benefits to me. a never ending life, the apex predator to humans, biting necks, the ability to attempt the destruction of wealth and capitalism, and, as iwtv depicts, hot gay sex and love in every era.