Okay, I did it for Phil and now I'm doing it for Genesis. Of course, it's a bit harder with Genesis because there are more albums to choose from, and everyone likes to divide the band's career into specific eras. Is it possible, then, to pick one favourite opening song from the band's entire career while resisting the urge to pick a favourite from each era? I think so.
For me, the greatest opener also happens to be my favourite Genesis song of all time: Mama. It's a song that I never tire of hearing and, having just completed a fan edit of the song I've finally realised that, great googly moogly, this really is my all-time favourite Genesis tune. There's so much power and atmosphere in such a relatively simple song, from Mike's drum machine (which starts on the back-beat, unwittingly giving the song an off-kilter feel) to Tony's moody keyboards and Phil's heavily compressed vocals (channeling his inner John Lennon). It has a claustrophobic feel until the drums come in and the dam bursts open.
In the book Chapter And Verse, both Mike and Tony talk of Phil and Peter's ability to give a little bit more in the final third of a song. Supper's Ready, The Musical Box and No Son Of Mine come immediately to mind. The most impressive example, though - for me - is Mama.