I love both hotels! I would vote with your son, though. It's nice to try something different, and DLH has lots of very cool things going for it that make it special. If you find that you still prefer GCH, then you'll know which one to book next time. I have trouble deciding which of the two hotels I prefer...sometimes one, sometimes the other. On my most recent trip to DLR, I stayed at PPH for the first time. Not a fan, but what I was going to tell you about our stay was that, since there isn't anything at PPH (whole pool/spa area was closed and there are no grounds), we walked over to DDT through either GCH or DLH. We found ourselves specifically targeting DLH almost every time! They have great dining options, a cool bar area, and more family-friendly prices. The outdoor areas are wonderful! There is a beautiful large outdoor fireplace now and Trader Sam's/Tangaroa Terrace are great. Your 7-year-old will love the waterslides and pool, I bet. You're also very close to good DTD dining options and entertainment as well as the monorail. I do prefer the rooms at DLH to those at GCH, too, and they are more kid-oriented. Goofy sometimes hangs out at DLH, or did before the renovation.
GCH is fabulous, but I would give DLH a try and see what you think. My kids love both but DLH was the definite favorite until this year (they're now 11 1/2 and almost 9).