Unfortunately its very unlikely that anyone is going to have been to more then one groundschool provider so its going to be very hard to find an un-biased view.
If I were you, I'd decide if I wanted distance or residential. The ATPLs are a LOT of work, if you think that you can do it with little guidance at home and really want to save money then distance maybe the best option for you. Are you someone that likes to actually have lessons and be taught what is important? If so then residential is the way to go. Then visit the schools your interested it, see what the instructors are like and what the subject books are like and decide which you prefer!
I went to Oxford and cannot rate them more highly. Awesome instructors who really know there subjects, and have so much experience in their fields. The OAT books are also in my opinion the best around, really clear and concise with excellent diagrams. However like you say they aren't the cheapest!
Good luck whatever you decide!
