As someone who has spent way too much time playing these games and probably more money than I should have spent on buying chips I have bought from just about all of the popular sites out there. Momschips is without a doubt the most professional one Ive come across...
I get that a lot of dealers out there have issues with cargurus but as a car buyer I had a good experience. I especially enjoy seeing car listings like you would see Home listings on Zillow, price drops and all. The app on Android could use some updating though.