In a band Like Genesis where two great Rock vocalists take the band in very different directions over time, you almost have to consider it as two bands. Peter Gabriel's Genesis was much more classic prog with mixed rhythms and Yes/Zeppelin-esc vocal lines. Of course Gabriel's voice isn't comparable to either band really, the classic style that make albums like Foxtrot and the Lamb the favorites of many Genesis Die-Hards.
On the other hand, As a Die-Hard myself, my favorite Genesis album will always be Duke. I feel like I relate to that album as if it were a childhood friend. I love every songs and lyric on it, and yet it is the beginning of Phil Collins' 80's pop trending. I find that Phil's voice has a smoother yet more passionate tone to it, as opposed to Peter Gabriel's rasp and frantic dynamic shifts. Phil brought prog and pop together, which I believe is a constant struggle of all prog artists these days. Simply, how do you get the common person to listen to a complex prog song? you make it relatable to the masses (Invisible Touch, Genesis, I Can't Dance are all good attempts at pop, but the band by this point has strayed so far from the original sound to be more mainstream.
So my argument? I'm sorry fellow Die-Hards, but I love Phil. Just an amazing voice with great precision. Phil seizes to let me down in his solo career to this day. I never would have loved that disney remake of Tarzan if it wasn't for Phil's Voice.