This must be your lucky day, because I've stayed at all 4 with 2 toddlers!!!! Here is my thoughts on each, in no particular order:
GF - This is a nice resort, very convient to the MK, but in my opinion I felt weird here. It might have been since we were staying in the main building and to get back to my room, I had to cut through the lobby in my bathing suit!!!
My kids liked it, but getting to Epcot from here is a nightmare, to monorails, usually takes an hour!!!!
WL - This is my favorite resort, we're also DVC members here, so we stay here a lot. This is a very relaxing place, you really don't feel like you're at WDW here. I always feel removed from the hustle bustle of the parks while here and it relaxes me!!! Quick boat launch to MK, can just roll strollers on/off so just as convient as the monorail. We've never had a problem with bus service, but there have been reports of long waits. The main pool is great, but the pool by the villas is better in my opinion. Bubbles coming up from the bottom, and NEVER crowded like the main pool.
AKL - THis is my 2nd favorite resort!!! It also is just as relaxing and removed from WDW as the WL. Sitting on my balcony and watching the animals was AMAZING!!! The pool also was great. I did feel like the MK was a far commute, but not that bad. If you're planning on spending a lot of time at MK, I might think twice about staying here. I'd never hesitate to stay her again.
YC - The best pool on property!!! SAB is GREAT and with the sand portion in the kiddie area, the kids just love that!!! I had a bad stay here, and wouldn't stay here again, I'm staying at the BC this summer. If you do decide on the YC, make your only request to be near the elevators. I didn't and was about as far as you can get from them. About a 7- 10 minute walk every time. Wasn't that bad in the mornings, but with tired children and adults was a bit long for me. The closeness of Epcot and MGM is great, we always walked to both, thought the launch took too long.
Let me know if you have any further questions!!