AKL for sure. My kids loved it in Dec, and talk about how cool it was to see the animals when they woke up and before bed! The biggest knock I've heard on these boards about the AKL is the distance to the other parks. IMHO it's really not that bad. They tend to have more buses running on it's routes to make up for the distance. So instead of waiting 15mins at a bus stop and a 10min ride, you might have a 10min wait and a 15min ride.
I've stayed at the WL and really enjoyed it but it took awhile to get to the parks. MK buses weren't going(refurb the bus stop at MK), and shared buses to the different parks. That being said I would stay again at the WL in a heartbeat. It is a great resort!
The Poly, I wish I had a chance to stay there, but as of yet I'm still dreaming. So I can't comment on the resort but the monorail to the MK would be great with little ones!
I really don't think you can go wrong with your choices, pick the resort based on your kids schedules and the parks they/you would like to visit.
Lots of naps and lots of time at MK = Poly
Lots of time at MK = Poly/WL
Even time between all parks = Any
Equal time between resort and parks = AKL
Just my .02