I have a RS map, but it is too general. Would be nice to get more details.
Every hotel I have ever stayed at in Paris over decades gives away free maps (advertising on the back) which are perfectly adequate. Same applies to most other tourist cities.
One good choice would be the Streetwise Paris map, which you can order here or elsewhere. A bookstore might also have one you could inspect first (and buy there if you like it). I like Streetwise for its detail, compactness, and durability. They also offer a separate Metro map, though I think the Metro lines are shown on the regular map.
For more detail and other information, Michelin has a "Paris par Arrondissement" booklet with excellent maps of each area, an index, good Metro and RER maps, and info on markets, pharmacies, bus lines, and much more, all in multiple languages. Try Michelin's website or a good bookstore.
I don't know why our host bothers with those "planning maps." They can help with planning the outlines of a trip, like the sequence of cities, but they're not much good for actually finding your way to a particular place or figuring out where you are when lost. We shouldn't have to depend just on smartphones or the kindness of strangers.
I'll second Dick's suggestion of the Streetwise map.
It has the main streets and some smaller ones but occasionally there will be an alleyway missing, lol. I like it because it folds and fits nicely into my purse. I can pull it out, back into a doorway and not have to unfold the whole thing. It's laminated so I can look at it when I'm eating and spills are OK, lol!
It has all of the central Paris core but doesn't go out to the edges of the main arrondissements so if you are staying out a way it might not be helpful.
I will second the use of Michelin's booklet on Paris. Small but readable - complete with alleys, metro, etc info. Before our trips, I mark places (apartment, museums, anything of import) with small colored stick-on dots to avoid having to look up locations elsewhere. Helps get to the right place with minimal effort. And the wife also has one in case I am abducted by a beautiful movie starlet for exotic experimentation on geezers.
I understand that the starlets also prefer the Michelin maps. They have access to a special edition that identifies prime geezer locating territory. Despite best efforts I haven't been able to find these areas where the starlets lie in wait. ;-)
Paris Par Arrondissement
I have a Paris Streetwise map, but I personally find this one more useful. Berndtson & Berndtson . I just found that it is out of print but you can find it used on Amazon.
I would use google maps on your phone.