I bought my used Tiguan through Maple with a trade-in. Their process was fine, everything was very fair, the pick-up wasn't so great though.I haven't bought a car from either dealership but Maple VW and Martin Grove VW both took excellent care of me and my MK6 GTI service wise
My intake manifold failed (common mk6 issue) and Maple VW still covered the warranty even with a Stage 1 tune they even did a carbon cleaning while they were in there for half price since they had to remove the manifold anyways.
Martin Grove VW always works around my work schedule and they shuttle me to and from the dealer to my work, and actually give me pretty solid deals/discounts on service .
cant speak about purchasing a car from either but I would definitely check them out when I'm in the market to buy again