Dream Theater - When Dream and Day Unite:
This one sort of explains itself. It's not that any of the songs on here are terrible, but rather terribly unmemorable, aside from a select few.
The Mars Volta - Octahedron:
I think most fans would regard Noctourniquet as their worst, but I think that album has a little more going for it and still has its moments. This one is still perfectly listenable but struggles to maintain a sense of direction. It simply sticks out as the least memorable of their albums for me.
Godspeed You! Black Emperor - Yanqui U.X.O.:
I think it speaks leagues about Godspeed's body of work when my least favorite album of theirs is still rather enjoyable. However, I don't think it compares to the rest of their discography and I do have to be a special mood to listen to it. Yanqui sounds much more sparse than previous Godspeed releases, which I can understand some listeners being more into. It's, to my ears, geared to sound more like an early Silver Mt. Zion record, which isn't a problem at all, but I don't feel the writing to be as consistent throughout as on a record like, say, Lift Your Skinny Fists.
Slowdive - Just for a Day:
I can't really say that Slowdive's discography is all that extensive unless I counted all the EP's as well. With only three studio albums (and possibly a fourth on the way), Just for a Day is still a good listen every now and then. Spanish Air and Catch the Breeze are some of my favorite songs in Slowdive's entire catalog, but I feel their other two albums to be much stronger still. One of my issues with this album is that, later towards its second half, it begins to sound more homogeneous, whereas an album like Souvlaki has plenty of variety and excels in each sounds as well.
Agalloch - The Serpent and the Sphere:
I liked this album more when I was first listening to it last year, but I don't think it's aged all that well for me. It's still a good listen to get through; the riffs are tight, the instrumental passages are climactic and tense, and John's growls are still sick as hell, but I think what it's missing is the atmosphere that was so strong in previous Agalloch releases.
Iron Maiden - No Prayer for the Dying:
I actually love the title track, but not a lot of the rest does a whole lot for me in the slightest.