Anecdote from this past Tuesday, for what it's worth: At a Starbucks in Buenos Aires, Rappi was set up at the table next to ours, doing interviews to hire delivery people.
A friend who uses these services more than me said he likes Rappi because you can see in real-time where your delivery is.
There's no Uber Eats in Buenos Aires yet though, and it would probably be a pretty dangerous endeavor given how violently taxi drivers have been reacting against Uber drivers. Any person on a bicycle or skates with an Uber logo on them would essentially become a moving target for some frenzied taxi driver to run over.
A friend who uses these services more than me said he likes Rappi because you can see in real-time where your delivery is.