Since Austin kicked out the big boys (for reasons that mystify me.) Over the last week I've experimented with Fare, as well as Car2Go and Fasten.
Here are the differences:
Car2Go is great if you live in central Austin. You need to be able to park near where you live and where you work or shop or whatever so all those places have to be inside the 'blue zone' which is on a map in the app. I live outside that zone, so I cannot park at my house (I could park but it will keep charging me until I park inside the zone). That makes car2go not work for me.
Fare is great if you want to schedule a ride, such as to make sure you don't miss a meeting or the airplane. But it costs more and has a tipping option, which some people get stressed about.
Fasten is the best for avoiding driving hammered in town.