I have stayed at and enjoyed all three of the onsite hotels at
Disneyland. The DLH is hands down my favorite, for the oversized rooms, pool area, grounds(the other two have very little in the way of grounds), Disney theming and dining options. To me, the distance is not a factor, our room at GCH due to its location within the hotel wasn't that much closer to Disneyland than our rooms at th DLH have been. For sure the lobby of the GCH will be closer, but your room may not! But the GCH is amazing, in my opinion it, and not the Grand Floridian in WDW, is Disney's flagship resort. I also love that the GCH has balconies. But for my family, the DLH is our sentimental favorite. I also love the fact that at DLH, you are guaranteed a third bed option. Either a daybed or rollaway (rollaways are free by the way). At GCH, you may get a bunkbed room (but taller teens cannot fit into those) or a daybed. If neither of those is available, you get a sleeping bag. For the price I pay, I want my son not on the floor.
My two cents on tripadvisor is that its a helpful site. However you have to take its reviews, especially reviews on Disney owned hotels with a grain of salt. Disney hotels are top dollar (even the value resorts in WDW are pricey compared comparable offsite motels). The prices and the very name "Disney" sets people up for what can be very high expectations. At any Disney owned hotel, you are paying for the location, the theming and the Disney name. Tripadvisor is a site often visited by deal hounds who can't get past the fact that for sometimes hundreds less, they could stay on Harbor in a room as close to the parks. To me, the onsite hotels are worth it and have never let me down in over 10 stays. Also, a bad review is always more likely to be posted than a good one. I like a lot of the amenities that the Disney owned hotels have (interior hallways, room service, themed pools with slides, bell services, and onsite dining choices. I also like being able to take advantage of early entry each day its offered and the package delivery. Even the Mickey wake up calls are worth some money shelled out for me! But if I was just looking for a place to stay and was expecting something in the hotel itself so out of the ordinary, I might be disappointed with what I paid versus what I got.
I'll further add that you generally see a ton of negativity on Tripadvisor on the onsite WDW hotels as well. And I have never had a bad stay at any of those either.
I'll also add that to me, being able to enter the parks through DTD vs. a busy city street is huge. I like not having to leave the magic behind. But if I was just basing my opinion solely on needing a place to lay my head, the pricetag of a DLR onsite hotel might make me write a different sort of review on the Disney hotels!