Here's one that will no doubt have the majority disagreeing with.
Anna Lee is a top-20 song in Dream Theater's catalog.
There is so much to love in a song that has such a simple instrumentation. John's playing (lap steel, if I am not mistaken -- guitarists correct me) is just FULL of soul, Derek paints such an emotional landscape with his opening chords and throughout that song, and James singing is simply beautiful. And it is one of the few times when I hear Portnoy playing a very slow song, that he's not overplaying. He provided the absolute perfect percussion to the tune.
I know its not something typical for Dream Theater to do. Something simplistic like this. (Although they have similar simplistic songs, they are more rare, obviously). But its so incredibly emotional, and a high point, at least for me, in their huge catalog of tunes. Sometimes, less is more. They nailed that on this one.