The only reason I use Garmin Connect is to allow my HRM data to upload to Strava.
I belong to a club that has as one of it's perks free mebership to RWGPS. The club rides are on that platform. I have been fooling around with making my own routes then exporting to my Garmin. At least in my experience, making rides to upload to the GPS is easier on Strava than it is in RWGPS. For me at least, in RWGPS making routes is a little bit finicky. But that might be my computers.