I like Adventure even though it lacks MM's motivation. It's got "Days," "The Dream's Dream" and "Glory" though. Hell, none of its songs are bad.
I like October even though the band would probably like to forget that period (they were all considering breaking up the band to join religious groups and Bono lost his lyrics sheet and had to improvise lyrics for the album)
A lot of people would probably throw Reggatta De Blanc in there, but I wouldn't. I really like it in spite of lame filler like "Contact" and "It's Alright For You."
I know that Siouxsie And The Banshees' Join Hands is often thrown in there, but I've never heard it. I only heard their first album, which was good enough.
If it counts, Use Your Illusion has one of the weirdest legacies of any "sophomore" album ever, unless you count the infamous GN'R Lies as their "sophomore" album.
You know I've just got to say it: I've never cared that much for Led Zeppelin II, or at least about half of it.