You can always do both, they can export to each other. Personally I moved to Strava about 3 years ago and much prefer it.
Do you know how I would export to Strava?
Quite a few ways, the easiest is with whatever software your device syncs with. For example Garmin Connect will export to both platforms. If you are using just a phone and want to sync to both platforms directly then you can use https://tapiriik.com/ Your other option is to do a manual export and import.
You can export gpx or whatever the choices are from the desktop endomondo website.Do you know how I would export to Strava?