Newbie here, and, while I am late to the party, I can't resist adding my two cents.
For me, the 70s was the greatest era for music for many reasons. I lived the decade, from ages 5-15, and I truly discovered music during this time. I started the decade with an AM transistor radio that I'd sleep with under my pillow (going through countless 9-volt batteries), to ending the 70s with a stereo that boasted a turntable, tuner, and dual tape deck. I began the decade listening only to AM stations (and, how cool was it that late at night, I could receive signals from stations as far away as New York and Chicago?? I grew up in the Cleveland area), then discovered FM about midway through the decade, and that really blew my mind. During AM radio's regime, the stations were truly psychotic in what they played-- you'd hear Elvis, followed by Marvin Gaye, then Jim Stafford, The Who, Dolly Parton, America, and so on. Stations were programmed not by a giant, faceless (and, I would argue, tasteless) corporation, but by actual programmers hired for each station, and all genres of music were played on each station. FM was even more awesome; stations may have compartmentalized a bit into a format, be it pop, rock, hard rock, etc., but the programming was still left to each station and to the listeners, who called in requests that were actually played. Another novelty--whole album sides were played, as well as deep tracks off albums that were not played on Top 40 stations. Not to forget the DJs themselves--and Cleveland radio had a ton of excellent ones.
Not only was radio fantastic during the 70s, but so were all the genres of music that came out: cheesy, sappy ballads, one-hit wonders, rock, hard rock, disco (yes, I really liked a lot of the early disco that was basically rooted in R&B. Once disco became huge, and everyone from Barbra Streisand to Ethel Merman made disco records, the genre became a parody of itself and mercifully died.), glam rock, arena rock, and punk grew and expanded during the decade.
Hands down, my favorite decade of music is the 70s--even today, I listen to that music more than any other. I loathe today's music, and feel sorry for kids today who grow up listening to all the AutoTuned garbage and don't know any differently. I am so grateful to have grown up during such an awesome time of music.