Tome of Battle: Book of Nine Swords
There where 4 initial polls for WotC products. B9S was in the first one: core rules. This was the poll that got the most votes. Here was the results, ranked by votes
Unearthed Arcana I LIKED 275| 0.714285714| 0.8899676
Spell Compendium I LIKED 241| 0.625974026| 0.8607143
Draconomicon I LIKED 231| 0.6 |0.8461538
Magic Item Compendium I LIKED 214| 0.555844156| 0.8136882
Libris Mortis: The Book of Undead I LIKED 212| 0.550649351| 0.8412698
Lords of Madness: The Book of Aberrations I LIKED 211| 0.548051948| 0.8577236
Manual of the Planes I LIKED 190| 0.493506494| 0.7630522
Fiend Folio I LIKED 187| 0.485714286| 0.7957447
Expanded Psionics Handbook I LIKED 186| 0.483116883| 0.7294118
Monster Manual II I LIKED 186| 0.483116883| 0.7018868
Dungeon Master’s Guide II I LIKED 179| 0.464935065| 0.7246964
Monster Manual III I LIKED 178| 0.462337662| 0.7385892
Book of Vile Darkness I LIKED 174| 0.451948052| 0.6744186
Oriental Adventures I LIKED 170| 0.441558442| 0.7142857
Tome of Battle: The Book of Nine Swords I LIKED 146| 0.3792207790| .5959184
Book of Exalted Deeds I LIKED 120| 0.311688312| 0.48583
Arms and Equipment Guide I LIKED 117| 0.303896104| 0.5223214
Monster Manual V I LIKED 115| 0.298701299| 0.6216216
Rules Compendium I LIKED 104| 0.27012987| 0.6419753
Tome of Magic: Pact, Shadow, and Truename Magic I LIKED 103| 0.267532468| 0.4951923
Monster Manual IV I LIKED 94| 0.244155844| 0.47
Deities and Demigods I LIKED 89| 0.231168831| 0.3787234
Miniatures Handbook I LIKED 85| 0.220779221| 0.410628
Epic Level Handbook I LIKED 76| 0.197402597| 0.2867925
Dragon Magic I LIKED 73| 0.18961039| 0.4424242
Weapons of Legacy I LIKED 60| 0.155844156| 0.2803738
(out of order) Magic of Incarnum I LIKED 54| 0.14025974| 0.2903226
Elder Evils I LIKED 43| 0.111688312| 0.4387755
Exemplars of Evil I LIKED 28| 0.072727273| 0.2745098
Enemies and Allies I LIKED 25| 0.064935065| 0.1602564
The first percent is of total voters that liked. The second is the percentage that liked that had an opinion. Which meant that 40% voted they did not like B9S.
What stands out is that it is solidly in the middle. This is also true when you compare its %s to the other polls. Like I said, about 40 products got higher %s, either in terms of overall voters, or those % of those that expressed an opinion on the product.
And when I look at the winners, I am not surprised. Eberon was mentioned above. Do you really think B9S has had the same kind of impact Eberon has? Or PHB II? Or the Warlock from Complete Arcane. Do you think it has seen the kind of use that the Spell Compendium has? And it definately doesn't get the "love" that some like Draconominicon has. I think the polls are on to something.