One other benefit at Pop is it is actually a tad bit cheaper too (the taxes are lower there).
That said, we stayed at ASMo and it was great. We were in the Toy Story buildings and they were quiet, close to the main pool and the loby area. The dalmation building is about the same distance but has the added advantage of being close to both pools. I've heard that those buildings tend to have a lot of kids, and groups... so they can get pretty loud. The Mighty Ducks building is the location of the 2nd pool, which is usually less crowded. It is further from the ASMo lobby area and food courts, BUT it is pretty close to the ASMu food courts and bus stop. So, you could head over to ASMu to catch the bus and beat the lines at ASMo.
A note about the transport, I did not see that big of a problem with the bus sharing with the All-stars. Yes you are sharing with 2 other resorts, BUT they have more buses running. One night there were 2 All-stars buses loading up people and 1 more waiting to pull up to load more. Meanwhile at POP bus stop, the line was about the same size but only 1 bus there.
Overall, I think you'd be fine at either one.