There is a 50% chance that your bus service is going to suck no matter where you stay Value to Deluxe. It's the nature of bus service.
I personally don't like the décor of POP or AoA (stayed at AoA but not POP). So I'm already predisposed to have them last on my Value list.
But here's the thing. Everyone will tell you that POP has it's own bus and doesn't share (well there has been at least one trip report where AoA and POP did share a few times over their week stay, but right now that seems to be rare) and that makes them better.
But,
POP is huge with more rooms and more guests and only the ONE bus stop. All stars are smaller and only share maybe 2 or 3 rides out of 10. I've only shared buses at ASMu twice in two trips. Statistically the AllStars will have less people on their buses so less crowded and therefore better chance of better bus service.
The only other advantage is that the Allstars are sisters and close together. 3 food courts 6 pools and three activity schedules all within a 10 minute walk. POP and AoA are not sisters so your chances of using the better AoA pool is iffy since they do at times lock the gates to the feature pool and let only AoA quests into the pool to swim and do activities.
All things being equal, I'd just find the best price and the décor you like the best and go. For me that has been ASmu. Less in your face giant icons, not as kid popular so there seems to be more adults, and you're right in the middle so easy to walk either way to the other resorts.