Depends on what is important to you, they are both great places. GCH has the entrance right into CA which is terrific- that is it's biggest selling point for that hotel if you ask me. It is a very beautiful hotel, but to us, since we are WDW vets, it is pretty much a scaled down version of WL. I think we would be a lot more impressed with it, if we had not stayed at WL a bunch of times. DLH has bigger rooms. We've done the DLH pool view rooms, and really liked the pool view we had from our room. DLH has the Trader Sams bar. DLH has the monorail slides and one other slide if you have littles, but DD got bored with those really fast. The lines are too long for the short slides. We can go to the public pool with a slide in our town, and it is a better slide with a shorter line. They look good, but don't expect them to keep a kids interest for long.
We always wind up picking the DLH because we like the rooms and room size and we like that it feels totally different from anywhere at WDW, but I don't think you can go wrong with either. Now, if it were a GCH theme park view room, I would say that probably can't be beat- but I've never been able to make myself cough up the extra money to do that one!