Back from a USA drive using our phone & tablet for mostly offline navigation. There is no one best nav app.
Although having access to various apps, we found ourselves using Here, Waze & Google.
Neither routing or time estimations varied much between them.
The biggest driving nightmare was crossing Los Angeles labyrinth of freeways. How the various apps do the lane guidance and what information is displayed is very different. One may show an exit number, another the exit to road name. The freeway signs were occasionally inconsistent showing one or the other.
Lane guidance? My wife would frustrating say I’m in the wrong lane (“Google is very clear”) as I’m following a different Here lane guidance. Here’s guidance often required ‘situational interpretation’, whereas Google’s apparent clarity was not allways.
Here WeGo - Does most things reasonably well. Also used it for public transport. My preference for offline.
Search not as good as Waze, but goes online to search if available.
Waze - best in the city. Best spoken instructions. Best for live messages about incidents ahead. Fastest route update when you don’t follow instructions. Inconsistent & often wrong speed zones. Doesn’t describe some intersections as intersection if you are going straight through. Hides all extraneous detail so it looks simple. That’s good for some, but I like more information. Does some weird routings occasionally. No offline.
Google Maps - no speed, so I wouldn’t use it. Arguably the best lane guidance.
TomTom - ugly. Everything works, nothing special. Offline search is very limited. Has very small map files and lacks detail compared to the others.
Sygic - frustratingly the car hands free always wanted to dial out when Sygic was running. The sound connection was more important than using Sygic so we gave up on it.