Hi Dale! It would be great to see you again.
I have been using Gaia for years and still like it. I so have onX as well. I use onX more for finding curated trials and Gaia for just straight up mapping.
Same. Gaia for all the trips, but OnX as a supplement for things like recent imagery (helps with early season and checking the snow regression), and seeing where things cross into private land (as frequently GAIA has led me into areas that though they public access, private land owners will throw up a locked gate, or block it someway. though illegal, doesn't help us if we're short on gas and have to re-route too far)
Pros-
OnX- user interface is nicer on the surface, easier to use, curated trails with recent conditions (if folks take the time to do it) and photos, Seems to be getting better at a much faster pace than GAIA especially for our purposes. nice overlay with temp for areas. easily distinguished snowmobile only roads in winter mode. Elite members get great discounts. (25% off Method for example... so one purchase of rims will save you the cost of a year of elite), better satellite map mode and hybrid mode, easier to manage folders/routes, sharing routes/folders with other onx users is super simple
GAIA-super customizable, tons of layers to tell you all the info you want/need. Can download any size map (only limited by device memory and layer size) can save to external memory card, Better topo map mode. more detailed topo maps (they have historic map layers too), super easy to export folder (route+waypoints)
Cons-
OnX- Maps download are limited to very small (for high detail) and odd shapes, no saving to external memory. Personally have had issues with the map going all black, despite map and gpx being downloaded for offline use. only way I've been able to avoid it is by going into offline mode (in the app not to be confused with airplane mode on the device)... but it's difficult to remember to do, especially when you go out of service when you don't expect (only happens when I go out of service, lock the device like at a stop, then open it back up) has happened on 3 different devices. that's the #1 killer for me... I have to be able to depend on it. Not as much route info as Gaia gives, speed, heading, ascent, decent, ect unless recording. At times it can be difficult to export a folder (route+waypoints).
GAIA-can be overwhelming to use, their folder management is a PITA, Android Auto Version, App Version, and Web version are all different and limit what you can do. I mostly use App Version, but planning routes can be difficult due to simple things like adjusting routes. Web version is great, so I end up going into the web browser on my tablet to make it easier. sharing with other users is not as nice as OnX, but isn't bad.
overall, neither is a bad choice IMO... my issue with OnX is the black screen issue, but though i've read others have this issue as well, no one I've run into on the trails has experienced it... so I chalk it up to me winning the undesired lottery.