we have a 5 year old and a 1.5 year old.
We like staying at the contemporary so I am sure we will like BLT, the monorail is great for kids. Our son calls it "Chattanooga." You have Chef Mickey's right there, and you can monorail to the MK and back, and you can change on monorail to go to epcot.
Our favorite is probably the wilderness lodge, we like the boat to MK, you can roll the stroller right on the big boat. The pools are fine, there is a lot to do in the lobby. Our son calls it "Humphrey's House."
After that, we like the beach club. Storm along bay is great. And you can walk to epcot and the studios, or roll the strollers on the boat. Our son calls it the "little mermaid house." He loves the kiddie slide there in the little pool. Listen, you just aren't going to be able to beat that pool for kids.
Our son also likes animal kingdom lodge, which he calls "the lion king house," but the bus is a hassle to me with the stroller. With two stroller age/ carrying kids I wouldn't want the hassle of the bus. But you do have the animals right outside, the pool is good and has a zero depth entry, and the kids like the little playground there.
OKW is actually a good alternative, there is a lot of room, you can park right outside, and the pool is OK and there is a good playground area. It is the only studio that you will have two beds.
We haven't stayed at boardwalk since we've had kids, but it would be about as good as beach club, with access to the two parks. The pool wouldn't be as good for the little ones, but there would be the boardwalk to walk around.
If you have a car and are driving to the parks, just go to okw. If you are taking transportation, stay at one of the MK or Epcot resorts. That's just me.
Honestly, if you can swing the one bedroom you'll be glad to have the dishwasher and washer and drier. With three kids and car, an OKW 1-bedroom would be better than a studio at blt in a lot of ways to me, but without a car no.