I've said since I started using Apple Maps in its beta, that it gets a bad rap. I travel all over the country, and it rarely lets me down directions wise. I used Google Maps before AM came out, and I don't see a difference in accuracy. I'm not saying that GM isn't better in places, but in some places AM is better. I think some people have issues like one poster whose given up on AM because his house location is off by a mile, but they don't stop and think, hey I'm one of 7 billion people, so statistically there will always be people whose house is off by a mile. On GM and on AM, just get it corrected.
GM does seem to have the edge on location data, which isn't a big deal to me, but I'm sure it is why a lot of people use GM over AM on an iPhone. But for me, I like the Hey Siri, take me home feature a lot more.
If you step back and think about it, both AM and GM are impressive apps and both have room to improve. But I do not think one is far superior to the other overall.