RATP vs Citymapper
For a very long time, I relied on RATP app to help me navigate the public transport system in Paris, however I have come to see it having some limitations in the options it provides through I still use it for the Bus timetable.
I now use Citimapper which I find it exceptional at managing a tight timetable and helps me gain time during my travels.
The suggestions provided by the app are also very helpful, focusing not only on the time the train arrives, but on which car you should board so as to be closest to the next connecting train or where to exit on your chosen street. Even better is it showing you where the closest bike, scooter or e-scooter sharing locations are.
Often it is getting out of the winding tunnels of the metro stations that takes the most time. Citymapper helps to take some of the guesswork out of it. It used to be that the app Paris ci la sortie du metro was the go to app to help get out of metro stations, bonus that it worked offline.