Strava will run almost any Garmin, but has apps for both iPhones and Androids so can you dispense with investing in another gps cycling gadget.
What Strava offers that other sites don’t is the ability to create segments of rides…climbs, descents or sprints…whatever, and then it will rank your ride through those segments on a leaderboard when compared to other riders data submissions.
It will cover most of the other data you’ve uploaded to the likes of GarminConnect, training peaks etc..it will capture Watts from a powertap, providing you have a recording device, they will even estimate Watts per weight of rider/bike and grade….
I’ve found using it this year, it provides a better gauge of my fitness when comparing segments, and teaches you how to budget your efforts better so you can be there at the end to contend.