I cancelled a Priceline reservation at YC a few weeks ago. It was super easy to do through Priceline’s website/app. No phone calls necessary. Like you, I noticed the AP discount rate was essentially the same price. Less if I pay with discounted Disney gift cards. Priceline refunded my credit card in, IIRC, about 3 days.
With all things being equal, I feel more comfortable booking directly with Disney. I figured why have a middleman if there is no benefit? Throw in the opportunity to pay with discounted Disney gift cards and it was an easy choice for me.