I love this idea. I actually did this thing a while back with all I've Sound albums to see which was my favorite.
But now for the Ayu albums...
Spoiler:
A Song for XX
1. prologue 4
2. A Song for XX 7
3. Hana 5
4. FRIEND 6
5. FRIEND II 8
6. poker face 4
7. Wishing 6
8. YOU 4
9. As if... 6
10. POWDER SNOW 8
11. Trust 5
12. Depend on you 6
13. SIGNAL 7
14. from your letter 3
15. For My Dear... 4
16. Present 6
Average: 5,56
LOVEppears
1. introduction 7
2. Fly high 9
3. Trauma 7
4. And then 8
5. immature 6
6. Boys & Girls 7
7. TO BE 8
8. End roll 10
9. P.S II 6
10. WHATEVER "Dub's 1999 Remix" 7
11. too late 8
12. appears 10
13. monochrome 8
14. interlude 8
15. LOVE ~refrain~ 5
16. Who... 10
17. kanariya 4
Average: 7,53
Duty
1. starting over 7
2. Duty 8
3. vogue 9
4. End of the World 8
5. SCAR 10
6. Far away 5
7. SURREAL 10
8. AUDIENCE 6
9. SEASONS 8
10. teddy bear 7
11. Key ~eternal tie ver.~ 7
12. girlish 8
Average: 7,75
I am...
1. I am... 8
2. opening Run 6
3. connected 10
4. UNITE! 6
5. evolution 9
6. Naturally 9
7. NEVER EVER 10
8. still alone 7
9. Daybreak 6
10. taskinlude 7
11. M 10
12. A Song is born 4
13. Dearest 9
14. no more words 10
15. Endless sorrow ~gone with the wind ver.~ 10
16. flower garden 5
Average: 7,88
RAINBOW
1. everlasting dream 9
2. WE WISH 8
3. Real me 10
4. Free&Easy 9
5. Heartplace 9
6. Over 8
7. HANABI 9
8. taskinillusion 8
9. everywhere nowhere 10
10. July 1st 8
11. Dolls 10
12. neverending dream 7
13. Voyage 8
14. Close to you 8
15. independent 9
16. + 7
Average: 8,56
Memorial Address
1. Angel's Song 9
2. Greatful Days 6
3. Because of You 9
4. ourselves 8
5. HANABI ~episode II~ 8
6. No way to say 8
7. forgiveness 9
8. Memorial Address 10
Average: 8,36
MY STORY
1. Catcher In The Light 9
2. About you 6
3. GAME 9
4. my name's WOMEN 8
5. WONDERLAND 10
6. Liar 8
7. HOPE or PAIN 7
8. HAPPY ENDING 8
9. Moments 10
10. walking proud 7
11. CAROLS 8
12. Kaleidoscope 7
13. INSPIRE 8
14. HONEY 9
15. Replace 6
16. winding road 10
17. Humming 7/4 7
Average: 8,06
(miss)understood
1. Bold & Delicious 10
2. STEP you 9
3. Ladies night 10
4. is this LOVE? 10
5. (miss)understood 9
6. alterna 10
7. In The Corner 8
8. tasking 9
9. criminal 7
10. Pride 9
11. Will 9
12. HEAVEN 10
13. Are you wake up? 9
14. fairyland 10
15. Beautiful day 9
16. rainy day 9
Average: 9,19
Secret
1. Not yet 8
2. until that Day... 10
3. Startin' 8
4. 1 LOVE 6
5. It was 5
6. LABYRINTH 7
7. JEWEL 6
8. momentum 8
9. taskinist 9
10. Born To Be... 10
11. Beautiful Fighters 8
12. BLUE BIRD 7
13. kiss'o'kill 10
14. Secret 7
Average: 7,79
GUILTY
1. Mirror 10
2. (don't) Leave me alone 6
3. talkin' 2 myself 8
4. decision 8
5. GUILTY 5
6. fated 10
7. Together when... 10
8. Marionette -prelude- 6
9. Marionette 9
10. The Judgement Day 7
11. glitter 4
12. MY ALL 3
13. reBirth 6
14. untitled ~for her~ 10
Average: 7,29
NEXT LEVEL
1. Bridge to the Sky 10
2. NEXT LEVEL 10
3. Disco-munication 9
4. EnergizE 8
5. Sparkle 10
6. rollin' 8
7. GREEN 10
8. Load of the SHUGYO 8
9. Rule 7
10. identity 6
11. LOVE'n'HATE 8
12. Pieces of SEVEN 10
13. Days 9
14. Curtain call 7
Average: 8,57
Rock'n'Roll Circus
1. THE introduction 1
2. Microphone 9
3. count down 10
4. Sunset ~LOVE is ALL~ 7
5. BALLAD 8
6. Last links 10
7. montage 2
8. Don't look back 10
9. Jump! 5
10. Lady Dynamite 8
11. Sexy little things 9
12. Sunrise ~LOVE is ALL~ 10
13. meaning of Love 8
14. You were... 8
15. RED LINE ~for TA~ 10
Average: 7,67
Aaaaand the ranking seems to be...
1. (miss)understood - 9,19
2. NEXT LEVEL - 8,57
3. RAINBOW - 8,56
4. Memorial Address - 8,36
5. MY STORY - 8,06
6. I am... - 7,88
7. Secret - 7,79
8. Duty - 7,75
9. Rock'n'Roll Circus - 7,67
10. LOVEppears - 7,53
11. GUILTY - 7,29
12. A Song for XX - 5,56
So yes, it's now scientifically proved that I love (miss)understood. But other than that, this is all wrong. NEXT LEVEL shouldn't be that high - it's only there because the amazing interludes bumped its ranking significantly. On the other hand, Rock'n'Roll Circus should be in the top 3, but the atrocious interludes dropped it from glory. LOVEppears should also be much higher. But that's about it.
(Damn it took some time to do this. 
But it was fun!)