This is how it stands now.
1. TRAIN OF THOUGHT (2003)
2. METROPOLIS PART 2: SCENES FROM A MEMORY (1999)
3. SIX DEGREES OF INNER TURBULENCE (2002)
4. A DRAMATIC TURN OF EVENTS (2011)
This is based on a rating of each song, not the album as a whole. If I did it that way, Scenes would be #1.
Also, I&W is basically interchangeable with #4.