I'm a HUGE Genesis fan, one of my favorite bands of all time (Abacab and Wind and Wuthering are BOTH in my top album list of a any band ever, and the live "In The Cage Medley" is perhaps my favorite live song ever). So I think I have some insight here:
Point blank: I do not like the vocal work that Hackett, Banks and Rutherford did outside Genesis. I don't know why that is, but the vocals on all three of their catalogues (with one exception: the song Banks did with Fish) are very weak, in my opinion.
I do not mind "poppy" at all, so the first three Phil albums are among my favorites (he lost me when he turned into Phil Ochs or Sting; I don't care for his preachier work). Essential: Face Value, Hello I Must Be Going, and No Jacket Required (the pop hits, especially on NJR, can be tough, but the album tracks are STRONG).
I don't think Gabriel has put out a bad album (though everything since US has been spotty). I think Dave is right about "Passion". I think Peter straddles the line between "poppy" (or commercial) and progressive (in the true sense of the word) the best of all the members. Essential: Security, US, Passion.
Tony should only write lyrics for Phil or Peter to sing. I know, harsh. But his attempts to duplicate Phil, Mike and Peter's solo success don't work for me. Essential: A Curious Feeling, Sevens, Six...
I'm not a fan of Mike's solo stuff, or Hackett's. I know, I know, Hackett's a guitar god, but honestly, I see where Banks was coming from for the most part. Harsh, again, I know, but it's my opinion, and it's not like I think he sucks or anything, it's just that his songs aren't my cup of tea.