I have almost all the solo stuff by the "big six" (classic line-up plus Phillips), other than a few of the more recent Phil Collins and Mike + the Mechanics stuff.
Banks' solo stuff is a mixed bag....some really good stuff with some really mediocre stuff. His choice of vocalists wasn't always great. The classical albums are okay, but classical isn't my cup of tea....and Tony doesn't even really play on most of the cuts on the classical ones. Or if he does, you can't really hear him.
Collins' solo isn't my type of music overall. I love the first three albums when they first came out, but have a hard time listening to them now. Anything after No Jacket Required is painful for me to listen to.
Gabriel's stuff is very good across the board, but there's also nothing that I would consider essential. Every time I pull out one of his albums, I hear his melodies in my head for a month afterward.
Hackett has some truly brilliant stuff, but he's all over the place. Most of his albums have a combination of brilliant with mediocre to bad stuff as well. His last 4-5 rock albums haven't had any of those great tracks.
Phillips' rare rock stuff is actually pretty good. His primary area of semi-classical/new age/library music is pleasant, but ultimately forgettable.
Rutherford's solo stuff isn't my cup of tea at all. I liked Smallcreep's Day a lot when it first came out, but not so much these days, although I still enjoy it. The first Mechanic's album and Beggar on a Beach of Gold are good, but the rest of the Mechanic's stuff is pretty unlistenable to me