I've known of the OpenStreetMap project for a long time and it is indeed cool. I did not know that there were any good apps that made use of that data for iOS. So thanks.
There are a bunch of them. I just don’t know all of them since I use Gaia.
One thing that was brought up in the beginning of this thread is Android or iOS. Some apps are exclusive to each operating system. Gaia on iOS is nearly flawless. On Android a lot more people seem to have issues. I don’t know if it ends up being a hardware issue or what. Android is a much more diverse ecosystem with lots of different versions of the operating system as well. I think that makes it more difficult for developers.
If you have specific Gaia questions check out the thread I started a long time ago "Ask me about Gaia GPS". Lots of folks have jumped in to help.
Some other general comments:
Storage complaints - Not all of the available maps are vector based. That is dependent on the map creator and is not something specific to Gaia GPS. As vector based maps come available Gaia makes sure to make them available.
All Trails - Not a fan of the app. I paid for the pro version for a year and rarely used it. It is very hiking focused and more of the crowd sourced content is for hikes vs vehicle trails.
Map Legends - For Gaia they are available online.
Map Legends
They can probably be found within the apps help files but I never use that.
It was already mentioned but most of these apps are not meant for on road navigation. Use Google Maps, Apple Maps, Waze etc for that. As an individual you can add Google maps to Gaia (Google how to do this :) ) It is a nice layer for an overall view of a location. But there are plenty of other maps for this.
To each his own. I always welcome competition and try new apps all the time. I'm even willing to pay for them to try them. I personally am the wrong guy to ask about Android stuff. I have a nice LG Android phone sitting next to me and don't really use it. It's a backup device for me. I prefer the iOS experience. If you do too great. If not there really isn't a need to debate because each have their own camps.
I have used Gaia for over 5 years and have seen them listen to the community, learn what we as overlanders want, and implement them. I know more improvements are coming because Gaia constantly updates the app. They have a team working on the app all the time. Other apps are 1 person development shops and it just limits the ability to make changes and keep up with support.