I've been using GeoHopper (https://itunes.apple.com/us/app/geohopper/id605160102?mt=8) for many years with both ST and now Hubitat. I've had no issues with it and since official presence is still not out, I thought I'd share. It's very accurate and has the added benefit of being able to tie into iBeacons (the author of GeoHopper doesn't sell them anymore, but he may have some if you really want to buy one). I have one in my Garage and in my Car so I can send a lock command when I leave it (this is an API outside of Hubitat); the Garage one works to register that I'm getting ready to leave and to not trigger my cameras/PIR sensors when I leave the house (again, outside of Hubitat), but you can see the flexibility with an App being able to make API calls based on Geo location or iBeacons.
Idea is to create virtual presence devices as documented for each Location+Person (i.e. Home-Brian) and create the location in GeoHopper called Home and draw your circle around the location. Then install the app, select the virtual device(s) you just created, copy the URL (text it to yourself), add your name into the URL after Location (..../location/Brian?access_token=....), then plug that URL into a POST webhook within the GeoHopper App.