I’ve been using RWGPS since 2016. And Strava for a year or two. And Garmin Connect.
Practically speaking, route creation is about the same and they each have quirks and differences. Some other thoughts here: Alternatives to Strava Routing - #7 by WindWarrior
The big difference is I follow people on Strava and creating a route and downloading to my Garmin, that only requires a couple of clicks. Here in California I find it easier to discover interesting routes on Strava, by looking at key segments.