I've found Uber to be very poor in Buenos Aires: they started charging my card before the pickup, so I deleted that option... even so, pretty much every trip involves multiple cancellations, some of the drivers try to avoid cancelling (so I'll be charged), and the waiting time estimates in the application are huge underestimates.
I was regularly asked by the drivers before the pickup "where are you going", this is ridiculous, I input my destination in the app and there should be no reason to ask for it again. If the driver doesn't like the destination, then they will try to get me to cancel. For some time as well, the Uber app didn't show the licence plate of the car, this is a real safety concern.
I much preferred Easy Taxi, which worked with real taxis and was very reliable, but this service has been shut down by Cabify. The only time I tried to book a driver with Cabify they wanted 3 times the normal taxi fare to Puerto Madero, claiming high user numbers (this was at 5:30am), so I dropped that idea very quickly and got a taxi from the street. I don't think I'll be using Cabify any time soon.
There's a BA Taxi app that I intend to try.