See, I'm a prog guy, but there's a lot of prog I don't like. I'm a metal guy, but there's a lot of metal I don't like (other than Metallica, I find a lot of thrash to be one-note and cartoony). Like TAC, I seem to like it when DT does it; Train Of Thought took a long time to grow on me (I'm an Images and Words/Octavarium fan) but grow it has, and I like it today. It's still in the bottom third of the catalog for me, but I like it. It's hard for me to say that "I like this better than that", because it's all relative, but generally, if I'm going to put on a DT record, it's not going to be ToT, nor is it going to be any of the Mangini-era records. They just haven't clicked with me much.
I'd probably rate them like this:
1. Dream Theater
2a. A Dramatic Turn Of Events
2b. Train Of Thought
3. Distance Over Time
4. The Astonishing
But all of them are well below the crown jewels, which to me are Images And Words, SFAM, Octavarium, Awake, and Six Degrees.