I am not going to be much help as we are 50/50, we have stayed at both, last time in 2006 was pop and we are going in Feb 2009 and re-booked to go to pop.
My wife and I prefer Pop but my sons prefer ASMo [they are 15 and 19]. There is little to choose between them we have stayed at ASMo at least 5 times and only once at pop, we prefer pop becasue it is new, in my mind it is similar to both ASMo and CRB it is the best of both worlds, the rooms being new were nicer but I prefered the bar and pool area at ASMo, because the service at pop was extremely slow when we were there, but what swung it for us was the location, with the lake etc it was nicer to look at and walk about lol. [god I am getting old]
My sons prefer ASMo as it was like returning to see an old friend and they both felt more comfortable there and said in their opinion the food court was better and the shop also, but it is all opinion.
When we were in WDW Oct 2006 we had a few hours to spare and had decided to re-book so we went to ASMo for a few hours had something to eat and had a walk around, and we decided to book pop when we got back, it was also cheaper!!
I think it is personal choice and I would have no hesitation in staying at either, both have a lot going for them lol