I only use iOS maps, it wasn't bad when it first came out and is very decent now. But that being said, I live in an area that has a high population and thus very few defects in the area. In fact when it first came out I went to a site that listed tons of defects and most of them were simple, "flat bridges over water." Very few on missed locations.
That all being said, I did run into a section last weekend where it took me down a dead end road. I switched over to Waze and it was fine. BUT that road was just closed off a few weeks ago, and I did not report it to Apple although I should have. Waze is much more proactive on the reports.