I would go with the Poly concierge because everything would be at your finger tips. The volcano pool and beach are right outside your door, the lounge would be so convenient for a snack or drink for the kids, It is only a short distance to the food court. Just a boat ride to MK with the castle in sight the whole time. Monorail resort. Fantastic view of fireworks and castle from your resort. If you decide to splurge and upgrade to Lagoon View, you could sit on your balcony or even your bed and watch the fireworks. Huge room, queen beds and a daybed.
POR is a great resort, but really can't compare it to the Poly. The only thing that I really dislike about POR is that you risk being quite a distance from pool, food court, etc. if you get placed in one of the distant buildings. That was always important to us, especially with little ones.
For us, if budget allows, the Poly would be our choice.