This is not the most prosperous time in history. I'd say the 90s had better income equality, which alleviates most of these issues to a degree. The low cost of Chinese goods was a boon, but that later decimated domestic manufacturing and led to the false prosperity of the stock market serving as a final reminder of the prosperity we once all shared in America. Its the reasonable wages of those jobs we're missing now. Housing was less scarce too.

Pre ww2 America was similar to now from what I've read. I've disqualified the 70s and 80s due to inflation. The 50s are pre civil rights act. Perhaps the 60s are in the running? If you dont count the Vietnam war as detrimental to prosperity.