I guess it depends on what you define as "entertainment". There is true entertainment on the Boardwalk at night - jugglers and magicians - you can also walk to Fantasia mini-golf from there, rent a surrey bike, rent boats over at YC, etc. If that would interest you (my DS11 LOVES the Boardwalk), I would pick whichever is cheapest - YC, BC or BWI CL - as you can access all of these entertainment options from any of those resorts. You may also want to take a look at the pools to see which one interests you. My DS11 prefers BWI because he loves the loopty-loops on the clown slide.
If you would prefer watching fireworks at night, I would probably choose Poly. WL CL is lovely, as is AKL CL, but the pools at both of these resorts are a bit small for a tween. At WL, however, you can take a boat over to Ft. W to access the activities over there. We did this the week before Christmas a few years ago and made a night out of seeing HDDR and then taking a private sleigh ride around the resort.
The EP resort area, however, will be the liveliest, IMHO.