Everyone here has their own personal favorite. Some will tell you the GCH because of the how close it is, but realistically, DLH and PPH are 4 minutes further. Some feel GCH has a more upscale feel. To me, the lobby does.
It really depends on what you are looking for. PPH is a nice hotel. Rooms are large and bright with a surf motif. I hate the elevators, but others aren't bothered by it. To me, it doesn't have a resort feel to it. The new dinner buffet there is pretty good, but it is limited to that restaurant. That said, if you stay there, you still have access to the other hotels. Trader Sam's and Hearthstone Lounge are a 5 min walks and Steakhouse Lounge/restaurant is maybe 7. Same with Napa Rose, and Storytellers.
Disneyland Hotel - Has a resort feel, love the pools, love having characters on site to meet the kids, rooms are large, Mickey motif, love the light up head boards. One of the nice parts is you walk out of the hotel and you are step from DTD and while you have Steakhouse 55, Goofy's, the Lounge, Tangaroa Terrace and Trader Sam's right there, you also have Jazz Kitchen, Tortilla Jo's, Catal, Uva Bar and many others, steps away.
Grand Californian - Has a resort feel, pools are good, slides are better at the DLH, beautiful lobby, love listening to Jaime, one of the piano players, has Hearthstone lounge, Napa Rose, Storytellers, and Whitewater Snacks. If you exit from DCA, your room can be close. Exiting from Disneyland, the walk is about 4 mins shorter. The rooms all have a small balcony, the rooms are smaller and to me, they are dark. They are done in a woodland motif. Think Yosemite Awhanee Hotel. I've stayed here about 6 times, and the last time (about a year ago) I asked myself why I kept doing it when I don't like it? Because everyone keeps saying it is great, and I was trying to see it. So, I quit trying. It isn't my favorite. But everyone is different. I like a room with 2 queens and a sofa sleeper, they are really limited on those. you either get 2 queens or a queen and a bunk bed set. There are 39 rooms with the 2 queen/sofa set up. Otherwise, you get 2 queens and a sleeping bag.
All 3 can use the entrance to DCA for EE, but I recommend the main entrance.
You need to try the hotels for yourself as your needs and mine will vary.