Existing for eternity sounds worse than it just being over with. I can't even fathom the concept of eternity.
I believe that after death, you feel the same way you did before you were born. Nothingness.
That said, science cannot currently prove that the existence of an afterlife is a false one or a true one. Therefore, these are all just beliefs, not facts, whether you believe there is one or isn't one. It's still a belief system, regardless if you are pro or con.