I have the same problem with today as I did with Day 11. How to pick a favourite album, never mind a favourite song from that album. So I went with an album that I’ve owned for a long time and still listen to regularly, with a lot of amazing tracks.
When I was younger my best friend gave me a double compilation CD called Corrosion. It’s got loads of great bands on it, some I had known before she gave me the CD, and some that I was introduced to for the first time. It had a huge effect on my musical tastes, and probably a detrimental effect on my bank balance as I found albums by many of the featured artists.
It was hard to pick one song from the double album, but eventually I decided on 16 Stone Pig by One Minute Silence (although As Seen On TV by Pitchshifter was a close second). I hadn’t come across the band before, but went straight to Cockburn Street the following week and bought the album. I still love it.