I use both the Quint books and the splatbooks by WOTC. In general I much prefer yhe quintessential books, they are a 'better bang for your buck' despite being for a single class. A lot of the stuff in the class books by WoTC will not be appearing in my campaign, largely because of outright silliness. (An arrow that follows an unpredictable flight path doesn't get rid of Dex bonus, it just misses...)
When I first purchased the Quintessential Fighter my only reason to do so was the Open Mass Combat system. I had very low expectations and was in fact delighted to find very nearly the whole thing useful. Indeed I had to eat crow on that one and even tell people, 'this is a good book'.I pull it out now and again to point out that, yes, I can be wrong. I do impose both a cost in gold and an experience cost as well for the fighting schools, but I do use them in my D&D campaign.
The only book that seriously disappointed me was the Quintessential Rogue, I dislike the concept of 'rogue feats'. Even that was easily fixed, just opening them to all classes and adding a few prerequisites where I felt them needed.
The classbooks on the other hand waste too much space on Greyhawk prestige classes and random silliness. However they do have a decent amount of useable stuff. Tome and Blood in particular was very useful, and gets used fairly reularly.
As for the Oozemaster, not in my campaign.
The Auld Grump, who could fill several pages with comparisons...