what time frame or era + sport had the greatest group of athletes / rivals ?

[WorldNumberOne]

for me it's pretty close between 1970's nfl and mlb . so many great teams and players from that decade

can be any sport and any time frame .

like ali/fraizer/norton/foreman

or

1975 to 1985 mens tennis with borg / mcenroe/ connors / lendl and some others .

doesnt even have to be a 10 year time frame.