I love all the Disney resorts, from the values to the deluxes...for different reasons, obviously. We just returned from a stay at Music. Our room was in like-new condition and service was fantastic (not sure if this was due to the extended Pilot program). The grounds were in pristine condition (the complete oppositive of what we experienced at POR in July!!!) The kids enjoyed the "idea" of being able to participate in the pool-side afternoon activities and watching the movies in the evenings more than they actually did them. Still, it was nice to know they were on offer if we needed some resort entertainment for the kids.
This past July, we spent one night at Sports before heading over to POR. Our Sports room was so newly refurbbed that it still smelled faintly of fresh paint. The grounds here also seemed quite clean and well-kept.
While I loved Pop the last time we stayed there (over a year ago), I don't think I want to return until the rooms are refurbished. During our last visit, we noticed that things were becoming a bit worn and threadbare already. After more than 12 months and lots of visitors, I can only imagine how much worse it has become. Also during our last visit, all areas of Pop appeared to be understaffed. We waited in lines to check-in and purchase food in the food court and waited for luggage and towels to be delivered to our room.
As far as transportation goes, it's hard to tell. We've stayed at Pop when there have been huge lines both going and returning from the parks and when things were not so crazy. However, we never experienced a bus that was not completely full. At the All Stars, we've sometimes had to share buses with all 3 resorts. Thus, the buses could be quite full. However, we've never had to wait for the next bus (as we had to do many times for both POFQ and POR which share buses). When the resort is busy, the 3 All Stars do not share buses. Thus, there were times last week when my family was the only one on a Sports bus. There were also plenty of times when we had to stand.
My advice: choose the resort that appeals to you most (or offers the best rate

).