By request of hefdaddy42, rank the albums by lyrical content here

[MasterShakezula]

So, yeah, which albums' lyrics do you like and which ones do you think suck?  Here's how I'd rank them:

1. Awake
2. Six
3. I&W
4. F into I
5. Eigthalbum
6. D&D
7. T of T
8. BC
9. SC
10. Metro#2 (Electric Boogaloo)

Overall, I'd say I generally prefer their 90s stuff, in terms of lyrics, though the 00s stuff is strong up until System. 
Though I don't like the story in Metro, so it's last. 

[KevShmev]

1. Awake
2. I&W
3. WDADU
4. FII
5. 6DOIT
6. ToT
7. SFAM
8. BC&SL
9. OV
10. SC

[DarkLord_Lalinc]

1. Awake
2. Images and Words
3. Six Degrees of Inner Turbulence
4. Scenes from a Memory
5. Falling into Infinity (excluding you not me)
6. Octavarium
7. Train of Thought
8. When Dream and Day Unite
9. Black Clouds & Silver Linings
10. Systematic Chaos

[jsem]

1. Awake
2. SDOIT
3. I&W
4. SFAM
5. FII
6. TOT
7. WDADU
8. 8VM
9. BCSL
10. SC

[wasteland]

1. Awake
2. Images
3. Six Degrees
4. When Dream And Day
5. Falling Into Infinity
6. Scenes
7. Train Of Thought
8. Octavarium
9. Black Clouds & Silver Linings
10. Systematic Chaos

[j]

1.) Awake
2.) I&W
3.) WDADU
4.) SDOIT
5.) SFAM
6.) FII
7.) ToT
8.) SC
9.) BC&SL
10.) Octavarium

Off the top of my head.  This is hard because albums like FII and SDOIT have some of the band's very best and worst lyrics.  And SFAM's lyrics are fine, just nothing special, but they're constrained by the concept.

-J

[Millais]

surprised nobody has put SDOIT first, although perhaps not their best work in terms of lyrical content, for me it's always been the most interesting to listen too. Awake & Scenes from a Memory are both great however.

[IdoSC]

1. SDOIT
2. I&W
3. Awake
4. FII (especially the demos, as they exclude You Not Me's lyrics and add some masterpieces like Raise the Knife or Speak to Me)
5. Octavarium
6. TOT
7. SFAM
8. WDADU
9. SC
10. BCSL

Basically I think DT kinda lost it a little when they started making rules about lyrics (SFAM era), with 2 exceptions, a positive and a negative:
SDOIT - they just nailed it here. When I read lyrics, I'm also interested in the topic. Blind Faith, SDOIT itself, Disappear, Misunderstood, The Great Debate, and last but not least The Glass Prison...amazing songs lyrically, I just love this album on that aspect.

WDADU - while I do appreciate the lyrics here (SC and BCSL are the only albums where I truly cringe at a major part of the lyrics), they're just not as good as the other 7 albums. Too many songs by Dominici and Moore - and I don't appreciate the lyrics of either generally - and I've seen better stuff from Petrucci in the 7 albums above.

[Ben_Jamin]

1. 6DOIT
2. WD&DU
3. Octavarium
4. I&W
5. Awake
6. ToT
7. BC&SL
8. SFAM
9. FII
10. SC

[Infinite Cactus]

1.Awake
2.Images and Words
3.FII
4.WDADU
5.SDOIT
6.Octavarium
7.SFAM
8.TOT
9.BC&SL
10.SC

[abydos]

1. Awake
2. SDOIT
3. Images and Words
4. FII
5. WDADU
6. SFAM
7. ToT
8. Octavarium
9. BCSL
10. SC

[dethklok09]

1. Awake
2. I&W
3. WDADU
4. SDOIT
5. FII
6. SFAM
7. Octavarium
8. ToT
9. BCSL
10. SC
11. A Dramatic Turn of Events

[Gysten]

1. Scenes From A Memory
2. Images And Words
3. Awake
4. Six Degrees of A Inner Turbulence
5. Train of Thought
6. Falling Into Infinity
7. Octavarium
8. Systematic Chaos
9. Black Clouds & Silver Linings

[CrimsonSunrise]

1. ACOS (yeah...only an EP but it ranks higher then any single DT album for me)
2. SDOIT
3. FII
4. I&W
5. Awake
6. SFAM
7. Octavarium
8. BCSL
9. TOT
10. SC
11. WDADU

[Dcrupi]

Awake
A Change of Seasons
6DOIT
Images & Words
Falling Into Infinity
Metropolis Pt. 2: SFAM
Octavarium
Train of Thought
Black Clouds & Silver Linings
WDADU
Systematic Chaos

[Ħ]

1) Awake
2) FII - MP's best contributions, as well as LITS and TOT
3) IAW
4) SFAM - very "real" and "pedestrian" sounding, perfect for the concept
5) SDOIT
6) WDADU - KM has some real shiners, but mostly cheesy lyrics
7) TOT
8) SC - the fantasy lyrics really aren't that bad...it's just POW and TDEN that drag it down
9) Octavarium
10) BC&SL

I predict ADTOE will be in the 7-8 range.

[Metropolis Pt. II]

Favorite:  Awake

Least Favorite:  SC

Everything else is in the middle and I don't feel like racking my brain to organize them.

[wjc]

In approximate order

Awake
FII
I&W
6°
ToT
WDaDU
8vm
SC
SfaM
BC&SL

[manticore999]

1 -SFAM
2 - 6 doit
3 - iaw

The rest didn't do anything for me lyrically.

[Mbarak]

All great throughout:
1. Awake
2. I&W

Mostly Great with some iffy ones:
3. FII (NM, PS, HY, LiTS, TAMP, AL, ToT)
4. SDOIT (TGP, BF, Misunderstood, Disappear, Solitary Shell)

Mixed bag:
5. SFAM
6. WDADU

Mainly sub-par with rare gems
7. ToT (Vacant)
8. BC&SL (Wither)

Not one song with great lyrics, but some great parts within some songs
9. Octavarium (most of These Walls, MP's part in the song Octavarium)
10. SC (parts from ItPoE I & II)

[Daso]

1. Awake
2. Images and Words
3. Six Degrees of Inner Turbulence
4. When Dream and Day Unite
5. Falling Into Infinity
6. Scenes From a Memory
7. Black Clouds and Silver Linings
8. Octavarium
9. Train of Thought
10. Systematic Chaos

[LCArenas]

1) Six
2) Awake
3) Images
4) Falling
5) Dream and Day
6) Scenes
7) Octa
8) Train
9) Blacklouds
10) Systematic

[Adami]

Favorite:  Awake

Least Favorite:  SC

Everything else is in the middle and I don't feel like racking my brain to organize them.

Pretty much how I feel.

[Fran521]

1- 6DOIT
2- Awake
3- I&W
4- FII
5- 8V
6- WDADU
7- SFAM
8- ToT
9- SC
10- BC&SL

[tri.ad]

1. Awake
2. Images And Words
3. SDOIT
4. FII
5. WDADU
6. Octavarium
7. WDADU
8. TOT
9. BCASL
10. SC

[nikatapi]

1. Awake
2. I&W
3. FII
4. SDOIT
5. Octavarium
6. TOT
7. SFAM
8. WDADU
9. SC
10. BC&SL

[Mladen]

1. Six degrees of inner turbulence
2. Scenes from a memory
3. Awake
4. Images and words
5. Octavarium
6. When dream and day unite
7. Systematic chaos
8. Falling into infinity
9. Train of thought
10. Black clouds and silver linings

[Infinite Cactus]

1. Awake
2. Images And Words
3. SDOIT
4. FII
5. WDADU
6. Octavarium
7. WDADU
8. TOT
9. BCASL
10. SC

Is the 7 WDADU SFAM perhaps?

[MasterShakezula]

Clearly, he ranked Kevin's stuff as 5 and the others' stuff as 7

[tri.ad]

1. Awake
2. Images And Words
3. SDOIT
4. FII
5. WDADU
6. Octavarium
7. WDADU
8. TOT
9. BCASL
10. SC

Is the 7 WDADU SFAM perhaps?

Oh yeah, my bad.

[hefdaddy42]

1. Awake
2. Images & Words
3. Six Degrees of Inner Turbulence
4. Falling Into Infinity
5. Train Of Thought
6. Octavarium
7. Scenes From A Memory
8. When Dream And Day Unite
9. Black Clouds & Silver Linings
10. Systematic Chaos

[DejaVu]

Lets try this out...

1. Awake
2. Scenes From a Memory
3. Images & Words
4. Six Degrees of Inner Turbulence
5. Black Clouds and Silver Linings
6. Octavarium
7. Train of Thought
8. Systematic Chaos
9. Falling Into Infinity
10. When Dream and Day Unite

[Mr. Beale]

1. 6DOIT
2. Awake
3. I&W
4. SFAM
5. 8VM
6. ToT
7. FII
8. SC
9. WDADU
10. BCSL

[reo73]

1. Awake
2. I&W
3. 6d Disc 1
4. SFAM
5. FII
6. 6d Disc 2
7. 8V
8. ToT
9. SC
10. BCSL

No opinion on WDADU.  Also, I would rank ACOS as their best song lyrically.

[iamtheeviltwin]

Ranking lyrics is difficult, there are several different ways to evaluate them and none are completely satisfying.
Do they convey clear meaning?  Are they too literal? too poetic?  not poetic enough?  generate an emotional response?  easy to sing to?

I think any of my top 5 are pretty interchangable lyrically, but I gave the edge to the album with the most lyrics that I found a) evocative, b) memorable or c) singable.

1  - 6DOIT
2  - 8VM
3  - SC
4  - FII
5  - Awake
6  - ToT
7  - I&W
8  - SFAM
9  - BC&SL
10 - WDADU