I’ve used both PLL and ILL; I have not used Queen’s, though I am familiar with MANY people’s experiences with it. It’s my opinion that Serl’s is stronger in grammar concepts, while following the CM model. Queen’s, IME, is TOO gentle and it starts too early.
I just can’t speak more highly of the Serl’s series, b/w (which never hindered my children) or in color. Financially they are the superior choice; Queen’s you have to buy a new one yearly, whereas you can get one PLL/ILL hardback, and the accompanying teacher’s guide and use for all your children up to gr. 6. Huge difference monetarily, even if they were exactly the same. Even if you went with the new-fangled versions, either colored or the consumable, the cost benefit still favors Serl.
We did most of PLL orally, too, since I wasn’t going to have them do as much writing as they could have done, but the concepts still stay.
If you do a search on the forum, you will find a multitude of references to both series.
Rachel