......you could only choose your gender and the location and year of your birth, and you could not choose your existing life?
I expect no one will choose to be female, which is a separate discussion of its own.
Tahiti in the 1920s might be a good option.
America during or shortly before WW2 would mean I would be too young to get killed in the war, but then enjoy the prosperity explosion afterwards. Surfing in Malibu, for example. I imagine some here will report that was indeed a special time to be a young person.
Homestead Act and land rushes of the late 19th century. Wild West. Hard work but also freedom, clean air and water.
Elk hunting.