My two favorites are Earthmate (I have an inReach/Garmin GPS/satellite messaging unit) and for road trips, inRoute.
Earthmate is great because you can download pretty much the whole Western US to use offline. Then it changes the amount of detail as you zoom in. Much easier to read than Gaia. I upload GPX files from Funtreks and elsewhere, save favorite "way points" (really just landmarks or points of interest) such as mountains, photo spots, etc. I use it on my iPhone and iPad.
inRoute is like Google Maps on steroids. Lots of functionality. Too much to list here. But for a couple of examples - easy addition of plenty of waypoints including layovers (hours to days) at each waypoint. Charts that show weather (precip, wind, temp), elevation and even "curviness" along your route based on either distance or time traveled. But, like Google Maps, it needs to have a data connection.