I have used both Avenza and Gaia and actually like them both. However I now use Gaia with a premium subscription for almost all my maps. I use the iPad for navigation in my truck and my iPhone for hiking. I'm always amazed at how many maps and many outdoor type apps only work when on the grid. With me, I'm off the grid about 90% of the time once I'm off the highway and beginning the real adventure.
There are some special maps that you can get with Avenza but not with Gaia. However the opposite is true as well. These are usually speciality maps. For example I can get a BLM map of the Alabama Hills on Avenza that shows the locations where movies were shot and I cannot get this on Gaia and DVNP had a specialty map that clearly showed legal locations for dispersed camping. So its actually nice to have both applications.
But like I said, Gaia premium is my go to now. If you search the web for a Gaia GPS promo code, you will find some pretty good discounts for the premium subscription. I got a 5 year premium membership for $130. For me that's a no brainer. Yes, I'll have to renew in five years but if I'm still around, I'll be more than happy to reup. The amount of maps that are available make it worthwhile as well as the ease of use. Just the Forest Service and Nat Geo maps are worth it. But you get so many more.
With Gaia, once a map is downloaded to one device, they automatically sync to your other device. This is true for routes, tracks and waypoints. Create a route on my Mac and it syncs to the iPad and iPhone. To create a route, just create waypoints that just snap to the road or trail that is shown on the map as long as you're connected to the internet. But once a route is created on line, you can download the route along with the map of the route. Also once a route is created, the mileage and elevation gain and lose can be seen for the route.
Sharing GPX files is pretty easy as well.
There is a downside to both apps: In the event of an apocalyptic event, such as a zombie attack, real navigation skills suffer as a result of the blue dot. So whenever I have a chance, I try to keep up on my trianglation skills with a paper map and compass. I still do my general planning with paper maps.
BTW, I also have no problem with my gps signal.