We've stayed at every All-Star. Pop for only one night.
We recently got back from All SS. I don't care much for the Theming, but like I've said before the resort and our room looked so new and it was so clean it sparkled, lol. Everyone was nice, friendly and helpful and the food court was good, so that made up for the sporty icons which I don't care for.
I think All SS is the least popular of the values, but it's a great place to stay, IMO.
On our previous stay we were at ASM. The room was rundown, but I've heard it was recently refurbished (just as Sport was) so it's much nicer now. It has some amenities like movie nights -but Music and Sport are welcome to participate.
I think that of the All-Stars, Movies has the best theme. But it hasn't been refurbished, and it shows.
The All-Stars can share buses, Always picking up Sports first, and Movies last. But I don't see it as a problem, because when it's busy -like park opening and closing- each one has its own bus. I think the Values have great bus service.
Finally, Pop. Only stayed there onle night so I can't say much. It looked great. I didn't care for the food. But Pop it's the favorite around here. It has great themeing.
HTH. Whichever resort you choose, have a great time!