I have to admit, I have never actually thought about this before. I love Genesis, have almost their entire catalog on vinyl and CD and have seen them live a few times.
Calling All Stations - Just kidding
A Trick of the Tail - this album was the first Genesis record I ever heard, and I was immediately hooked for life. It’s not just my favorite because it was first though. I feel like as a band they poured everything into making this great, knowing that they would be under a microscope with the sizable loss of Gabriel. And it worked. The changing time signatures of Dance on a Volcano, the sweet melodies and the rich 12 string textures of Entangled, on through to the drum featuring finale of Los Endos, this album delivers.
Abacab - this was the very first CD I ever purchased back in 1986 or so. That pressing has all of the characteristics of a CD pressed before people knew how to master for CD, but the vinyl isn’t nearly so harsh and allows the songwriting to shine and the album has a warmth to it that CD never delivered. The horns are a fun addition, but I’m glad they moved on to Phil’s solo career rather than being a mainstay of Genesis. Regardless I think this is the high point of the threesome version of Genesis.
Genesis Live - This album is incredible. IMHO every song on this is superior to the studio versions. There isn’t any other album by any other band where I would claim this, generally I am not a fan of live albums. But this album has an energy to it that makes these songs endure in a way the studio recordings do not. Love love love it, and third might be too low.
Wind and the Wuthering - I love the rich textures and full sound this brings. Tony Banks is really starting to explore the synth as an instrument, and Steve Hackett is still with the band. I understand why he left, but I think it was a big loss to their overall creativity and sound. Genesis with and without Gabriel are different but I like both. Genesis without Hackett is not as good as Genesis with Hackett imho.
Trespass - I know this isn’t going to be a popular pick with Anthony Philips and John Mayhew being on this record rather than Hackett and Collins, but I really enjoy listening to this one. As the years have gone by I find I listen to this one more than those that follow in Nursery Cryme and Foxtrot. Of course the Knife is still better in Genesis Live.
My honorable mention would be Invisible Touch. It’s nothing like the rest of their work but is one of the best pop albums of all time. Five top five singles plus the prog rock domino and the jam session Brazilian and the upbeat anything she does with a topic too risqué for radio play at the time. It’s a great album by any measure.