Best Downloadable Map for Phone

For offline maps and pedestrian and bicycle navigation I use the App “OsmAnd” that utilizes OpenStreetMap data.
For city navigation the free version should be fine, for hiking I would recommend the paid version that includes contour lines.

It’s powerful but not that easy to use, thus test it before you really need it.

HERE WeGo is a good alternative to Google Maps. It"s the navigation application used in most cars with built-in GPS.
You can pre-download the maps to use it without any connection network.

https://wego.here.com/

In Paris: Citymapper

https://citymapper.com/paris

I use both HereWeGo and CityMapper religiously and recommend them both.

In HereWeGo, the map you want to download for Paris is called "Ile de France." I also like to create a "Collection" where I save places I want to go - my hotel, museums, restaurants, cafés, shops etc. The app will sync across your devices so you can say input your items on a laptop where you have a big screen, then when you open your app on your phone, they will be there when you navigate to your collection!

I use organic maps. It too uses the OSM database, but it's optimised for walking and cycling. It's useful in that it doesn't track you, either.

Citymapper App is fantastic

please also get a "real" map since it never crashes and gives you a better overview, either ripped from a guidebook as noted or just buy the folding Streetwise version from the Amazon

Thanks for all your help. I think I'll do both Citymapper and take a "hard copy" map with me.