I am actually going to defend Quintessential Fighter, at least the revised version. They fixed a lot of the power gaming fighting schools by adding an experience cost. And it introduced the Mass Open Combat System rules, which have become a mainstay in my campaigns, though I have since switched to the OMCS2 that Mongoose introduced in Strongholds & Dynasties (sadly the only part of the book that I have used so far).
I have liked most of the class Qunts, with Rogue being the least loved. Rogue only feats were a bad idea, they should have tied the feats to skill levels or Rogue abilities instead. I ended up houseruling the changes in. Quint. Witch is pretty cool, though I had to tone down the witch sword... it was stupidly overpowered. I skipped Chaos Mage and Psychic Warrior, as they don't fit any of my games, and I never purchased the race books, for no really good reason - they just never grabbed me.
Take a look at the Powerclass books as well, Hedge Wizard has largely replaced adept in my game, I just wish that they had done a 'Hedge Priest' as well.
The Auld Grump