I carry the Rand McNally Motor Carrier's Road Atlas and a RV and Camping road atlas (National Geographic maybe?) in the RV. The two have different key information, first about the types of roads, the second about recreation and camping destinations.
For most of my non-RV travel I prefer the Michelin road atlas because the maps are arranged geographically and have the same scale, rather than being organized by states and scaled to try to fit a state to a page. That's for general planning. In each state I'll have the road map issued by each state, usually either the highway map or the tourist map, for immediate reference.
I use an automotive GPS to keep track of where I am. I don't use it to feed me travel instructions, my routes change on a whim, using the numbered U.S. highways and state highways, and county roads only occasionally, in the states where county roads are on the state maps. I will use the GPS (or my smartphone maps) for guidance on "how do I get from this hotel to an IHOP" or "where is the nearest ..." questions. I pull off the road for that.