I've been fortunate enough to have stayed at all or them... several times. And IMHO, unless you have a "favorite" (which I do - it's The Contemporary) I would suggest that there are several circumstances that could possibly dictate which one would be better for you and your particular situation.
For example: The Grand Floridian - never seems to get a lot of "kudos" here on the threads. But truth be told, it's always booked, so someone must like it ! I believe the people that like it have very particular reasons why they like it - and not just because it's "the most expensive" or "most opulent" - maybe, just maybe, it's because
it has everything... admittedly including the highest price, but
everything !
I love The Contemporary - first place I ever stayed at WDW... my "first love". What kid wouldn't love having a "futuristic train" (monorail) running right through his (or her) living room ! The amenities are nice, the lobby is super, talk about location (at least for MK), decent restaurants, monorail access, boat access, solid bus transportation, nice pool... and if you can afford (and can get) a room in the "tower" with a "Magic Kingdom" view, and your kids like fireworks, well... you'll be their hero forever !
Then you have The Yacht & Beach Club... of which I would highly suggest The Beach Club (even though they are actually "sister resorts and are connected). Bright, airy, child-friendly, great location to EPCOT and DHS (by boat - or walk) and simply super bus transportation every where else. Restaurant selections are good, but since the location is so proximal to EPCOT and DHS, you have all those restaurants to choose from, as well as The Boardwalk area and the Swan and The Dolphin Resorts.... Oh, and did I forget to mention that if your children like "water", then this choice would, again, make you "Supermom" ! Here you have "Storm Along Bay"... words can not convey the logistics of this pool, you should go to the "Yacht and Beach Club Resort" thread and actually see photos of it - only they can give you a real perspective of this fantastic pool.
You also have The Animal Kingdom Lodge Resort, The Wilderness Lodge Resort, and The Polynesian Resort to choose from. I would suggest taking a few minutes to review a description of each resort, find a map that can give you some prospective of each of there locations, check out the prices, amenities and benefits of each, and then make a first, second and third choice - once you have made the decision and you feel comfortable with your first choice, make your reservations; but I would also suggest doing this as quickly as possible because if you are looking at July, you might already have a problem in getting exactly what you want. I hope all this helps....