I've been using Endomondo for some time to track rides, hikes, walks, etc. With the Endomondo Apple Watch app, you can start a ride and track your stats from there. Ride and workout data syncs with the Endomondo iPhone app, and the Apple Activity and Health apps (if you setup Health app to allow access from Endomondo).
Soon as your ride is over, just stop the ride from the Endomondo Apple Watch app. Road and MTB cycling options are available. The only thing I wish they would add to the Endomondo Apple Watch app is auto pause. Not a big deal and maybe I've missed it in the settings, but the feature exists in the iPhone app so maybe that will come soon to the watch app. So, you could use the above (or with a similar ride tracking app that can integrate with Apple Activity and Health apps), and your Garmin Edge. That could be a nice combination to capture ride and exercise/health data.
The other benefit from using an Apple Watch while on rides is to stay in touch with family/friends. You can monitor and reply to calls and texts (stopped and safely pulled over of course). Super convenient and reduces the need to take your iPhone out of the jersey back pocket, or CamelBak.
I've been doing the above for over three years now with the original Apple Watch. So, I'd imagine that with a Series 4 watch, that the experience will be good for you. Battery is starting to fade on my original watch, so I am considering getting the Series 4 for the above along with the new features the 4 has.