Both are deluxe resorts, so in terms of rooms not much differance. Ive stayed in AKL and loved it, although Ive not stayed in the Poly Ive visited on numerous occasions, the beach area is lovely depends on what theming you want really, both are excellent. The poly is obviously closer to MK and on the MOnorail system, and im guessing if booked direct, the price would reflect this.
Personally Whatever you choose will be a great choice.
Jules