Sometimes a song will be special for me only because of it's past with me.
Example, Nitty Gritty Dirt Band's Ripplin Waters. During the height of my depression during the last half of the 90's I met this gal through chatting online through ICQ. She basically allowed me to escape my depression and made me feel better about being me. She liked Ripplin Waters, and suggested I check it out. I generally don't mind the song, but it's special to me, because it reminds me of her. She did more for me than the entire psychiatric profession.
Haven't chatted with her in years. She went through a messy divorce, but found herself a nice new chap. But I still remember her for how she helped me regain my sense of worth through just chatting.
Most of the songs I listen to, usually have a special reason attached to them for why I love the song.
With the exception of my obsession with Rush, no band has ever made their music my favourite based only on the strength of their skills. There has to be a personal connection to it.
In the case of Abba, I like it, because I had a wargamer friend (swedish) who used to play a lot of Squad Leader with me when it first came out. Today, whenever I listen to Abba, I am magically back in time when Squad Leader first arrived.
