While I've not really read the third party publishers, I have to say I liked most of the WotC books. MotW just had a whole lot of neat ideas. Menehirs, infusions, generally good prestige classes, awesome spells (I vastly prefer the regenerate path to the cure path for Druids, gives them their own spin on healing magic). I basically didn't read the fluff, "how to play your character" is rarely interesting in a generic light, I much prefer such stuff to be campaign specific, like in the Eberron CS.
T&B had a lot of neat ideas, though very few of them were carried out well in the mechanics, and the spells were useful but lacked the flavor that the prestige classes had. DotF was great for the magic armors, some of the prestige classes (though more were bad, enough were good to make it worth while), and while I don't like the prestige domain idea, they were interesting. S&F was, as someone here already said, not the way things went, but if it has any faults, they can all be understood in the light that it was the first of its kind, and for what it was it was great. S&S was awful, the only thing worth reading was trapmaking (which should have been in the original DMG) and bardic instruments, definitely not worth the money.