I'm biased against an age-related death. That aside, the premise of dying at the current mortality rate of 80 years, give or take, versus living forever is a bad one. It's too extreme a juxtaposition to be useful. "Forever" is a catch-all concept that doesn't do what a good question is meant to do:

Keep the questioner focused on addressing the primary concern. In Lex's case the question appears to be: Die at the current natural lifespan, or don't?

A healthy person can always choose to die. A dead person cannot then choose to live. The better the question, the better the answer.

My opinion: Lex's belief that death gives life meaning is premature and romantic. I have a lot of experience with death. I haven't found anything romantic about it. That notion is best left at the distance of fictional representation. I would much rather live a healthy life independent of death mandated by causes that seem preventable, like pathologies related to aging. I want the possibility of existential boredom. If that becomes untenable, I can always choose to die. That's the point: When it comes to death by aging, I am pro-choice.