This is easy... the decade when you were in your teens to mid-20's. Music to wash your car by, when you're in your 50's. The only difficulty is if you spanned two decades between your teenage years and mid-twenties, then you have to choose teen-angst versus mid twenties "maturity." I'd be curious to see if anyone breaks this rule...

The other exception is if you continue to enjoy popular music beyond your twenties... I could pick the 40's (when I was not a teenager, as easily as the 80's (when I wasn't in my mid-twenties.)

Jerry