It's all a matter of taste. There may well be someone out there who feels that the best album they did was From Genesis To Revelation and that everything after that was awful. Are they wrong for thinking this? No.
There are popular opinions and there are unpopular ones. I have found over the years that it's better to just let people have their say on what they like and what they don't like and not to challenge their opinion. Challenge leads to conflict as less secure people feel that they have to defend their standpoint by criticising what they don't like rather than praising what they love.
For me, there are two distinct eras for Genesis: 1970 - 1977 and 1980 - 1992. It matters less who was in the band during those eras but what kind of music was being made. Basically, the first era leant towards complexity and the second era lent more towards immediacy. The only constant through both eras was Tony, Phil and Mike. If you play in a band long enough, it's natural that you change, adapt, mature etc. And that, for me, is exactly what Genesis did.
What is amazing is that they weathered so many different musical fashions and trends, just ploughing ahead, doing their own thing, occasionally falling into step with what was popular at the time and then falling out of step again, never losing focus and, up to a point, maintaining a solid fanbase that seemed to grow from album to album.