Well, my immediate answer is the 1940s. I think the answer should be what decade we would want to live in, because I could technically say that I would love to have been a teenager anywhere between 1900-1950. LOL There is SO much variance in that time period, I need to choose one.
While I love all the pretty dresses of the 1910s (think Downton Abbey - This is a great article on the clothing for the show.), I love the era of the 1940s. The fashion was great, the music was excellent, the movies were awesome and the swing dancing was fun! I was a swing dancer in high school, and although I didn't compete or anything, I had a blast doing it. I love listening to Frank Sinatra, Bing Crosby, Judy Garland, ect. The movies! I can't even pick one! Meet Me in St. Louis, Singing in the Rain (okay, I know, that's from 1952, but still! LOL), Wizard of Oz (again, that's from 1939...lol), Casablanca, It's a Wonderful Life, ect - see! I can't pick one. I just love it. LOL I used to always say, I should have been born when my grandparents were born - 1925 and 1927 so that I could have been a teenager in the 40s. =)
Look at that swing move!
And the most important -
My grandparents on their wedding day June 1st, 1948. =)