Hell, I'll just rate them all right now.
1900s - Definite effort, but recording quality at the time was so terribad that it makes these songs hard to listen to. 5/10
1910s - Much better recording quality. Enough that music from this age has just the right amount of grain to feel rustic without being annoying. Lyrics would also deal with the horrors of World War 1, among other things. 8/10
1920s - A much more innocent time than the 10s. Slightly better recording quality, but not as complex lyrically. The standout, however, is that this decade marked the beginnings of the Jazz age, and that early jazz still sounds amazing. 8/10
1930s - By now, recording quality is a non-issue, and the jazz age is in full swing. Some of the greatest records of all time were born out of the 30s. 9/10
1940s - The 30s upswing continues. Swing and big band reach their peak during World War II, but even in their decline, we see the (extraordinary) beginnings of rock and roll and the golden age of crooning. Plus, 40s propaganda music is just fantastic. 10/10
1950s - The perfect intersection of the jazz and rock ages. I honestly can't decide whether I like this decade or the previous one better. They're both fantastic. 10/10
1960s - The Jazz age comes to a close, but the rock age gets dirtier and edgier in the advent of the Vietnam War. Also, Gospel and R&B become a thing, which makes this decade fantastic in itself. 9/10
1970s - The golden age of songwriting. Lyrically, this is the best decade in music. Other things, however, I feel have been lost with time. Sadly, Disco is now a thing. 8/10
1980s - Still a good decade, but even though early synthesizers sounded cool for some songs, I feel it got a bit overused. 7/10
1990s - Sadly, a majority of the few good songs by this point are those by acts still stuck in the 80s or prior. Computers are becoming ubiquitous in production, and boy bands are appealing to mass audiences. 4/10
2000s - What little good music there is by now is drowned out by megatons of absolute and utter shitey crap. Electronica becomes a major genre, which sucks almost all the fun out of music automatically. 2/10
2010s - What few good songs I can name from the present decade are nearly insignificant by now. Electronica completely dominates the mainstream AND underground scenes, washing away any remaining bastions of quality or effort. Almost nothing redeemable. 0/10