I have never stayed at the BC...but here would be my reasons to avoid it...
1. The pool is soooo large and it would be hard for 2 parents to keep up with those ages of children....more stressful for me.
2. The rooms are larger at the Poly and it has a food court as well as monorail access...our children are 9, 6, & 5 and they are still MK kids all the way...we spend the majority of our time there and it's GREAT to be able to monorail back to the hotel for a swim and be back in under 2 hours.
3. Our children LOVED the Poly's themed pool, the boat ride option to MK, feeding the fish off the dock, eating at 'Ohana's and heading back to our room, seeing the fireworks from the beach...etc. etc. etc.
I really want to stay at BC/YC eventually but not until my children are all over the age of 9 or so and I know I don't need to watch them every second in the pool.
Tara