My favorite feature is the gear tracker. I don't think it works on the new site so I've been using the classic version. It's good for keeping tabs on chains and cassettes. You can set the mileage you want to be notified on any piece of equipment as well.

Classic version

Click on Gear

I prefer mapping on Ride With GPS but I don't like tracking workouts on there. It requires GPS info or a map. Logging gym workouts is easier to do with mapmyride as well.